DNA TYPING AND IDENTIFICATION
Ever since 1953, when the DNA double helix structure was discovered by American scientist James Watson and British scientist Francis Crick, working together at Cambridge University, the world of molecular genetics has never been the same. DNA turned out to be a polymer (a large chain of repeating molecules), and a particular type of polymer at that, called a nucleotide (sugar and phosphate in a nitrogen base), and furthermore, the nitrogen-containing base (connecting the two sides) was arranged in the form of a palindrome (a series of letters or numbers that reverse themselves; ABCDEEDCBA or 1234554321). It therefore wasn't necessary to map the whole length of the double helix, which if stretched out would be six to nine feet long. It was only necessary to slice off and look at fragments or strands with one side of the helix where palindromes began and ended. Any one of these fragments, in theory, would be polymorphic enough (contain enough variation in form) to unlock the genetic code (genome) in its entirety. A few single strands should define how the other strands would look because each side of the helix was an exact complement of the other side, held together by what is called base pairing, the predetermined, palindromic fashion in which base molecules bonded it all together.
It didn't take long (1970 actually) for scientists to develop enzymes (called restriction enzymes) that would slice off fragments of a base pair at selected points. They then discovered that under electrophoresis, smaller fragments migrated toward the positive electrode, producing an autorad (short for autoradiograph) with fragments lined up from small to large. Markers of known DNA lengths could be placed in lanes of the electrophoresis gel to assist the lineup, and probes (radioisotope templates of known sequences) could be administered to hybridize the sample by bonding with sample fragments for better visual inspection. By 1985, Alec Jeffreys and his colleagues at Leicester University were calling these techniques DNA fingerprinting.
DNA typing, or DNA identification, is perhaps a better word for it than DNA fingerprinting or DNA profiling, but this varies by personal preference. In any event, Cellmark Diagnostics has applied to register the phrase "DNA Fingerprinting" as a trademark. At first, courts were quick to accept DNA evidence almost without question (under Frye or the relevancy test). Almost every crime lab in the United States wanted to make it a routine part of their work, and a number of private labs sprung up, mostly for paternity testing. Part of the 1994 crime bill, called the DNA Identification Act of 1994, set aside $40 million to help develop DNA capabilities in state and local labs, and also the Combined DNA Index System (CODIS Link #1 and Link #2) which is the national database for convicted offenders of sexual and violent crimes. There's a shortage of DNA Crime Laboratories in America. There are only about 120 of them, and they all have at least a year's backlog of work.
For the most part (outside of gross human error), the actual technology of DNA typing is considered unquestionably sound and reliable by the scientific community and the courts (U.S. v. Jakobetz 1992). Weak links exist mostly on the front end (crime scene sample collection) and the back end (presentation to jurors). Questions have also arisen about quality assurance standards and blind proficiency testing in laboratories. The most important legal issues revolve around the constitutionality of compulsory DNA testing at the time of arrest and the use of DNA profiling and population databases in police investigations. These are all Fourth Amendment issues and privacy concerns. Starting in 1999, for example, the U.S. government began taking samples of blood for DNA records on 99.8% of all babies born. Alarmed critics were quick to shout things like "bio-invasion", "nation of suspects", and "genetic criminal law".
It's difficult to grasp the significance of evidentiary problems without an understanding of DNA testing techniques or the principles of population genetics. Suffice it to say that states operating under Daubert or those that rejected or modified Frye in the first place are the jurisdictions where most legal battles occur, and a proper discussion of those battles would be quite lengthy (and constantly changing). I'll limit my discussion to the areas of discovery, jury instruction, and random match probability. Then, I'll walk you through some of the scientific techniques and principles (you may want to familiarize yourself with this glossary of DNA terminology).
DISCOVERY ISSUES
Discovery is a pretrial process where each side (prosecution and defense) shares their lineup of witnesses, what physical evidence they have, and what trial strategies they plan to pursue. It differs from plea bargaining because charges and penalties are not discussed. Discovery is informal, and depends on the working relationship between prosecutor and defense (typically, it occurs over lunch). By law, the only thing that must be shared by the prosecutor is anything that might shed light on the defendant's innocence (exculpatory evidence). This is called the Brady doctrine. Discovery is not a constitutional right, but a privilege. Defense should not rely upon a fishing expedition for "all Brady material", and if the process becomes uncooperative, the judge orders something called disclosure, a type of court-ordered discovery. There's lots of other similar pretrial processes such as suppression hearings and, most importantly, Daubert hearings (for scientific evidence). DNA evidence doesn't lend itself well to informal discovery processes because even though it has the potential to be exculpatory, DNA lab reports aren't exactly the easiest thing to discuss, challenge, or replicate. The reports either say "inclusion", "exclusion", or "inconclusive". They bring an unaccustomed degree of certitude to the courts. It may very well turn out to be the technology that overpowers the criminal justice system.
It's a trial nightmare with DNA evidence. Most everyone remembers the O.J. Simpson trial where DNA testimony was the longest part of it. It's often said that juries rebel against complicated scientific evidence. DNA evidence has the potential to be exculpatory, but DNA reports, with all their certitude in terms of probability, are used less for exoneration and more for confusion. The reports sometimes express probabilities out to so many decimal places that they cover the potential population of three or four solar systems.
What can you do if you're a defense lawyer and the report says "inclusion"? Well, before you try any last-minute strategies of claiming your client left their DNA at the scene by accident or during a previous visit (as you might with fingerprints), you'll probably want to obtain your own test, but this has the same self-incrimination effect as if you put your client on the stand, and in any event, further DNA testing will only cause delay and additional expense. About the only thing you can do is attack the lab for its (lack of) quality assurance and proficiency testing, or use a "Chewbacca defense" (thanks to the South Park TV show for this phrase) and try to razzle-dazzle the jury about how complex and complicated the other side's evidence or probability estimates are.
Forensic law is evolving in this regard, but pretty much doesn't favor the idea of fishing expeditions in the form of further DNA tests with the purpose of hopefully proving a defendant's "exclusion". Expense is only one consideration, at least in the pretrial stage. In the postconviction stage, expense is definitely a significant matter. Every inmate in every correctional system across America it seems, right now, demands a DNA exoneration test, at state expense, to prove their wrongful conviction. They also want to see the test results to analyze for themselves. However, there's no discovery or disclosure processes at the postconviction stage. There's a strong presumption that verdicts, especially those based on DNA evidence, are correct. The standard that appears to be emerging with the issue of postconviction exoneration (Link to Justice Department's 1999 Guidelines on DNA exoneration) is a hearing to determine if "reasonable probability" exists to vacate the verdict.
These "reasonable probability" hearings offer little hope to the potentially thousands of wrongfully convicted. First of all, it's important to understand what "wrongfully convicted" means. It includes repeat offenders who may have committed many (or related) crimes, but are innocent of the specific charge for which they are serving their present offense. It includes innocent people who, faced with overwhelming evidence against them, such as wrongful identification, perjury, or forged documentation, are greatly tempted to accept the plea bargain that their lawyer so strongly recommends. It excludes people who got "lost in the system," or were held without trial for long periods of time while being detained in a jail, out on bond, or simply awaiting charges (such cases are more properly termed wrongful imprisonment). It excludes those who are factually guilty but are found not guilty by reason of the exclusionary rule, or who have escaped justice because of some loophole, police mishandling of evidence, violation of constitutional rights, or reversal upon appeal (there is a difference between being "legally innocent" and complete exoneration because one is factually innocent).
DNA testing has only freed about sixty-three (63) people since the late 1980s. There's often resistance on the part of police and prosecutors to reopen cases. If we use it on inmates, how do we decide which inmates? If we use it on average citizens, are we invading their privacy? To prove a convicted person innocent, you'd have to do DNA testing on each and every person the inmate claims is the real perpetrator, all the likely suspects as well as a few other alibi witnesses. And then, of course, all the detectives at the crime scene have to have their DNA on file.
One of the more interesting cases with discovery of DNA evidence is People v. Castro (1989). Some consider Castro a new test of admissibility, but in effect, it avoids the whole admissibility issue and is actually a pretrial procedure reform. It sets up the following that must be shared in discovery:
copies of autorads (it's generally accepted that scientists can determine matches by looking at autorads prepared by another scientist)
copies of laboratory books
copies of quality control tests run on lab material utilized
copies of all reports issued by the lab on the case
a report by the lab on the method used to declare a match or mismatch (with actual size measurements used, both means and standard deviations)
a statement by the lab on the method used to calculate the allele frequency in the relevant population (this is the random match probability issue I discuss later)
a copy of the data pool for each loci examined
certification that the same rule used to declare a match was used to determine the allele frequency in the population
a statement setting forth observed contaminants, the reasons thereof, and any tests thereof
if the sample is degraded, a statement on whatever tests and results were obtained
a statement of any other defects, environmental insults, or laboratory errors, and reasons thereof
chain of custody documents
As you can see, this constitutes rather liberal discovery, and due process also requires that the defense have access to the assistance of a DNA expert (but this is imperfectly institutionalized, and another problem is that oral reports are not discoverable). For the courts, it's a better solution, however, than second opinion testing or preserving biological specimens forever. If Castro discovery guidelines are followed, any attacks on DNA evidence that come later at trial only go to the weight of the evidence, not its admissibility.
JURY ISSUES
Juries are intellectually overwhelmed by DNA evidence, and understandably so. Nothing in forensic science, except maybe mass spectrography, is as complex and complicated. Certainly, nothing has ever before been capable of producing odds like one in seventy thousand trillion (which might be the population of our solar system if all the planets were densely populated). Except for identical twins, the chances of similarity in DNA are astronomical or infinitesimal. As the O.J. Simpson trial demonstrated, the average American citizen doesn't respond well to advanced topics in molecular genetics. The issue is what jurors (and the general public) should be exposed to, and that debate properly centers less on the practical matters of jury instruction (about reliability depending on quality) or how many visual aids (pieces of demonstrative evidence) are too many, but instead on the whole matter of forensic science ethics:
a forensic scientist should never be dissuaded from a full and fair investigation of the facts
a forensic scientist should maintain an attitude of independence, impartiality, and objectivity
a forensic scientist should not tender testimony beyond the competence of the jury or laymen
utmost care should be taken with samples to avoid tampering, adulteration, or loss
reports should completely disclose any facts, opinions, or shortcomings indicative of innocence
testimony about tests and results should reflect opinions stated in terms of scientific certainty
even absent a request by the court or over the objections of a prosecutor, a forensic scientist should make themselves available to be interviewed by defense prior to trial [AAFS code]
For a moment, let's ignore the idealistic task of keeping things within the competence of the jury or laymen, and focus in the "whistleblowing" clause (all Code of Ethics have them). What would motivate a forensic scientist to "disclose any...shortcomings indicative of innocence"? Does this mean that any expert put on the stand should be forced to testify about how vulnerable their lab is to contamination, mismanagement, and incompetence? Well, the answer is yes, and that is precisely what defense lawyers have been doing whenever they get the chance. In the post-Simpson era we now live in, juries are regularly exposed to this rather than a short course in molecular genetics. Badmouthing America's crime labs has become the way to attack DNA evidence.
It's a defense strategy of putting the government on trial, reversing the role of who's the prosecutor, and trying the case in the media. The traditional ways of attacking physical evidence (tampering, contamination, and substitution) are replaced by the three C's for attacking crime labs: (1) contamination (really referring to cross-contamination in storage areas or the lab itself); (2) commingling (a lack of technician skill or proficiency at handling samples); and (3) conspiracy (inferring doubt about examiner bias or the planting of evidence). In fact, the following make for some common grounds of attack:
blind review/confirmation testing -- occasionally, technicians should be forced to run tests on samples they don't know anything about, but supervisors know what the results should be. Also, a confirmation test by another employee or at least a rescoring should be standard procedure.
flammables -- anything with a flash point of less than 200 degrees should be clearly marked and specially stored away. Fires are a special concern of crime labs.
glassware cleaning -- after use, glassware should be thoroughly cleaned, but there's lots of glass.
lead contamination -- any part of the lab involved in ballistics or indoor test firing will probably be contaminated and/or other trace minerals may be in the atmosphere.
machine cool down -- after use, lab instruments should be turned off as well as recalibrated
protective clothing -- employees should be wearing lab coats, safety glasses, and gloves
storage space -- overcrowding of evidence leads to leaving things in public hallways
ventilation systems -- use of regular or recycled air is bad. It's best to use once-cycled, filtered air where a constant air pressure is maintained and there's vent hoods over lab instruments.
RANDOM MATCH PROBABILITY
DNA typing produces what is called a random probability match -- sometimes as high as one in several million, sometimes as low as one in a hundred. It is defined as the probability of a match between a sample left at the crime scene and a suspect. Different methods of calculation produce different results, but it all depends on comparing sets of bands or spots on autorads. That is to say, there are two separate, but related issues: (1) the statistical methodology; and (2) the matching criteria. The latter is the closest thing to a margin of error, and it's usually stated in terms of requirements that the analyst observe "no more than a 5% difference in bands on the autorad" before declaring a match. Some experts have said that a 2.5% criteria would make a better cutoff point.
What statistical methodology is used also tends to be what one is comfortable with, and this is the area where DNA typing spills over into population genetics.
Humans have 46 chromosomes in their DNA, each one containing about 550 genes, and each gene containing as many as 35 alleles. A chromosome contains two complete sets of all genetic material. We're not talking about the two sides of a DNA molecule, just the chromosomes on a DNA fragment. At certain locations, there will be genes containing the same genetic code as the other side. These things we call "genes" are really locations (loci) on chromosomes. A thing called an allele is a specific form of a gene, an alternative form of a genetic locus. Alleles at locus points are inherited from parents, and there as many alleles as there is diversity in your family background. Chromosomes have the same loci all the way along their length, but may have different alleles at some of the loci. It's the alleles, not the chromosomes or genes, that are dominant or recessive, and give us things like eye color and blood type. The genes just give us medical diseases and other functionality. Alleles are characterized by slightly different nucleotide sequences and are distinguished by their different phenotypic effects. There's no known laboratory technique for determining a person's complete genotype (their entire genome). It can only be estimated by studying their family history or the outward characteristics they share with others in the subpopulation they belong (their phenotype).
In other words, genotype is inferred from phenotype, and you cannot neglect population substructure. To say that two DNA patterns match, without providing at least an upper bound of the frequency with which such matches might occur by chance, is meaningless. Testimony that the defendant's DNA profile would only be present in one out of 135 million African-Americans is meaningless when there's only 15 million African-American males in the United States. The solution is in the alleles, and particularly the frequency in which matching alleles are distributed in the genetic pool. Here's an example of the math involved with genotype frequency estimation:
The following table lists the numbers of individuals for each of the M-N blood groups in one human population. Calculate the genotype and allelic frequencies for each population.
population MM MN NN total
Eskimo 475 89 5 569
Here are the genotype frequencies that we calculate from the data.
These are our estimates of the genotype frequencies for the entire
population, obtained from relatively few sampled individuals.
frequency of MM = 475/569 = 0.8348
frequency of NN = 5/569 = 0.0088
frequency of MN = 89/569 = 0.1564
Allele frequency calculation
Method #1 (count individuals in the population)
p (frequency of M) = (475 + 89/2) / 569 = 0.91
q (frequency of N) = ( 5 + 89/2) / 569 = 0.09 (also 1 - p = q)
Method #2 (count alleles in population)
p (frequency of M) = (950 + 89) / 1138 = 0.91
q (frequency of N) = ( 10 + 89) / 1138 = 0.09 (also 1 - p = q)
Method #3 (use genotype frequencies you've already calculated)
p (frequency of M) = (0.8348 + 0.1564/2) = 0.91
q (frequency of N) = (0.0088 + 0.1564/2) = 0.09 (also 1 - p = q)
Which method is the correct method? Well, they are either all correct
or all wrong since each yields the same answer. Which one should you
use? That's up to you, depending on which feels most comfortable.
Population genetics assumes that population subgroups are homogeneous and mating randomly (Hardy-Weinberg equilibrium principle), which may or may not be a valid assumption. We know that African Americans, Caucasians, and Hispanics contain various subpopulations within themselves. Caucasians, for example, can be traced to different countries of Europe. What you need are population databases which act as an "ethnic ceiling" on those astronomical or infinitesimal odds you get when you just multiply DNA test results together by the multiplication or product rule. Let's take the O.J. Simpson case as an example:
1:240,000 Allele match with blood on sidewalk
1: 170 million Allele match with blood on driveway
1:57 billion Allele match with blood on gate
1:77 billion Allele match with blood in Bronco
1:535 billion Allele match with blood on glove
1:9.5 trillion Overall probability based on product rule
Now, nobody has that many alleles in their genetic history. You could even throw in a few genetic pools from a couple dozen or so outer space races and still not exhaust those probabilities. Oversimplified multiplication of allele frequencies is what accounts for all those astronomical odds you hear with DNA testing. Ethnic ceilings are determined by running tests on known subpopulation Blood Bank samples (e.g., Cuban Hispanics in Miami, African-American donors in Detroit). All you have to do is take a random sample of a population subgroup and count the number of times a given allele appears in that group. This "mapping" of the world's subpopulations is similar to the Human Genome Project, where only 5 out of 46 chromosomes have been completely mapped as of mid-2000. Ethnic ceilings tend to reduce random match probabilities to more reasonable levels, like 1:16,000 for Caucasians, 1:41,000 for African-Americans, and 1:19,000 for Hispanics.
The ceiling principle is designed to be conservative in estimating probabilities, providing a frequency which would not overstate the strength of the evidence. If a crime was committed in a particular area and the suspect belonged to a specific population group, the frequency for a certain allele might be higher than for the population as a whole. So it would prejudicial to the defendant to quote the population-wide frequencies instead of the specific ones. Some think the ideal might be to have databases tailored to specific crimes, but that would probably amount to mixing racial with DNA profiling. Controversy exists over this, and the fact that ethnic groups are not well defined, sociologically or otherwise. The FBI routinely collects samples from different states and has also worked toward a worldwide survey derived from databases around the world. It also uses a conservative fixed bin procedure which combines measurement error with statistical methodology. A "bin" is any number of base pairs having a certain length which is wider than the measurement error (2.5%) of the analytical system used. Alleles having that many base pairs (usually 872 to 963) are thrown into the bin, sorted, and probed using subpopulation markers.
Most modern DNA labs now have partially automated genotyping software. Computer based expert systems (such as STRgazer) have been developed to infer genotype from gene sequencers. These devices even do rescoring or confirmation testing, and a manual override switch allows the DNA analyst to conduct their own test. Given that the double result requirement is becoming standard, it would be a good thing for labs to require machine-scored results and human-scored results to match in some degree.
SCIENTIFIC METHODOLOGY
There are at least five (5) different forensic techniques to do DNA typing:
1. RFLP -- Restriction Fragment Length Polymorphism, the oldest technique, described briefly at the top of this page, essentially involving radioactive fragmentation and examiner comparison
2. PCR -- Polymerase Chain Reaction, a copying technique for small or broken pieces of DNA, which are copied or amplified, not cloned, and a computer or operator estimates match probabilities
3. STR -- Short Tandem Repeats (sometimes called VNTR, Variable Number of Tandem Repeats), a method which uses markers for short, repeating segments of microvariant allele patterns, as short as three to seven base pairs, usually involving computer expert systems although visual detection is possible
4. Mitochondrial DNA -- a type of PCR used by the Defense Dept. to identify war remains, or by archeologists on samples subjected to extreme environmental conditions, and since mitochondrial DNA is inherited solely from the mother, it has also been used in cases of disputed maternity
5. Rapid DNA ID Microchip-Based Genetic Detectors -- these are field-ready laptop analysis units capable of being used at crime scenes, displaying profiles onsite or electronically uploading to a CODIS database. The technology uses the same microchips that detect genetic diseases, but modified to transport, concentrate, and hybridize DNA via electric currents and to discriminate individual genetic markers
Most laboratories use the twin techniques of RFLP and PCR as part of their double result requirement. With RFLP, the DNA is chemically cut into fragments, pushed through a gel carrying an electric current, transferred to a nylon membrane, and then radioactive DNA probes are applied to bind with matching DNA sequences to create hybridized sequences. An X-ray film is then placed next to the membrane, and when the film is developed, a pattern of bands is revealed, called an autoradiogram, or autorad. With PCR, a chemical solution is added to the sample and boiled to remove the DNA, which is then combined with short fragments of known DNA, called primers, and other chemicals that stimulate replication by means of a polymerase chain reaction (mimicking the way nature replicates DNA). The replicated DNA is then applied to eight or ten spots on reagent strips, with each spot containing a different segment of other known DNA, and there's a match when a blue color appears on any spot.
With STR, certain known alleles characterized by relatively short base pairing are isolated at their loci with chemical markers. Then, through a process called PCR multiplexing, further such base pairs are both extracted and amplified, all the while ensuring that the size of the DNA fragments being analyzed do not overlap, thus eliminating the need for size markers, ladders, or the FBI bin method. The technology is based on knowing which loci contain what genetic markers for a given population subgroup. Some common genetic markers for the three main techniques are:
RFLP PCR STR
D1S7
D2S44
D4S139
D5S110
D10S28
D17S79 HLA-DQA1
LDLR
GYPA
HBGG
D7S8
Gc HUMTH01
D3S1358
vWA
FGA
A disadvantage of the RFLP method is that it requires a relatively large amount of fresh DNA. To develop the X-ray film also takes about a week. You have to do that for each analytical test, so the entire process can take many weeks. PCR techniques offer the advantage of requiring only trace amounts of DNA and they can be done very quickly. In fact, each cycle of the heating, cooling, and strand rebuilding with PCR doubles the amount of DNA, and takes about two minutes. When laboratories use RFLP they are only looking for five or six polymorphisms (North Carolina looks for eight), and by the time you have eight systems identified even with as few as 20 alleles, you are not going to gain anything by looking for more. By using probes (which recognize different repeating DNA segments), a high degree of near-individualism can be achieved. Probes have known allele frequency estimations in populations, so if you use four (4) probes with a frequency distribution of 1:100, then you can multiply the likelihood of your original match by the order of 1/100 x 1/100 x 1/100 x 1/100, or one in a hundred million. It's unlikely, however, than any two people would have the same profile based on probes of at least five loci. Probe technology is based on the use of reporter molecules to maximize the sensitivity of DNA analysis. The FBI uses single-probes while private labs often use a "cocktail" approach with multi-locus probes.
Some things that can go wrong mostly involve the RFLP technique, and include:
cross-contamination -- this can occur when accessorizing the sample or during the typing procedure. With RFLP, it shows up as sideways migration in the gel.
environmental insult -- biological or chemical contamination, as in bacteria, yeast, and fungal buildup. DNA evidence if fairly robust in this regard, however.
mixed samples -- this is the problem of mixed blood, common at crime scenes, between the victim and suspect. The autorad will show a superimposition of bands on top of one another, but PCR methods exist to screen out and amplify the different parts of the mixture if you have known samples from the contributors.
partial digestion -- sometimes the restriction enzymes don't cut well. Extra bands appear.
star activity -- sometimes the restriction enzymes cut too well. Extra bands appear.
band shifting -- when DNA fragments in one lane migrate more rapidly than identical fragments in another lane, causing an apparent mismatch. Causes unknown, but may be too much DNA or bubbles in gel
CRIMINOLOGICAL ISSUES
Criminologists tend to be interested in karyotyping, the study of the number and type of chromosomes. A major assumption of karyotype studies is that there's an abnormality of some sort causing the criminal behavior. The abnormality most often speculated about is the XYY pattern, involving an extra male chromosome. The XYY pattern occurs in about one out of every 700 to 1,000 males. The XYY male is usually over six-foot tall, exhibits low mental functioning, suffers from acute teenage acne, and is often clumsy. XXY males also occur, about once in every 500 males, but they have smaller genitals than XYYs and tend to have breast development. The XYY-crime link is a stronger than chance probability (for sex crimes mainly), but such people tend to be found in mental hospitals and prisons, perhaps a testimony to their mental functioning or clumsiness than their criminality. Nevertheless, in some jurisdictions, testing is done on juveniles to discover if they have the XYY genetic marker, and if so, it's used (controversially) as a predictor of risk for adult criminality.
Another area of speculation is whether or not there's anything like a criminal chromosome. This area is sometimes called mapping (for) the criminal chromosome, and you occasionally hear of a study searching for it. It is not, however, part of the Human Genome Project because that project is mainly devoted to discovering the hereditary basis of diseases and defects. It takes a lot of work to map a chromosome as you've first got to find subjects who haven't been exposed to a lot of environmental forces, like birth or dietary problems. It's also not a national priority to map for behavioral characteristics, the exception being mental illnesses like depression for which there's a strong lobby, but at least two forms of mental retardation (angelman syndrome and fragile X) have been mapped. The following shows what diseases or defects have been mapped as of mid-2000:
Chromo 1 - prostate cancer, glaucoma, Alzheimer's Chromo 12 - Zellweger syndrome
Chromo 2 - colon cancer Chromo 13 - breast cancer
Chromo 3 - lung, colon cancer Chromo 14 - Alzheimer's
Chromo 4 - Huntington disease, Parkinson's Chromo 15 - angelman syndrome
Chromo 5 - Werner syndrome, Burkitt lymphoma Chromo 16 - kidney disease, Crohn's
Chromo 6 - diabetes, epilepsy Chromo 17 - breast cancer
Chromo 7 - diabetes, cystic fibrosis, obesity Chromo 18 - pancreatic cancer
Chromo 8 - Werner, Burkitt Chromo 19 - atherosclerosis, dystrophy
Chromo 9 - melanoma, leukemia Chromo 20 - immunodeficiency
Chromo 10 - refsum, gyrate atrophy Chromo 21 - lateral sclerosis
Chromo 11 - diabetes, neoplasia Chromo 22 - myeloid leukemia
INTERNET RESOURCES
About.com: Law Guide to DNA Evidence
Barry Scheck's Innocence Project and Innocence Project Northwest
Basics of DNA Fingerprinting
Convicted by Juries, Exonerated by Science
Criminal Justice Implications of the Human Genome Project
DNA "Junk Science" Freeing Scores of Inmates (Truth in Justice.org)
DNA Testing: An Introduction for Non-Scientists
Examiner Bias in Forensic RFLP Cases/People v. Marshall
Frontline: Innocence, How Far will the DNA Revolution Go?
National Commission on the Future of DNA Evidence
NCSU Program in Statistical Genetics and Statistical Genetic Links
Postconviction DNA Testing: Handling Requests
Prof. David Kaye's WebPage
1996 DNA Report of the National Research Council (NRC II)
The Ethics of DNA Identification
The Unrealized Potential of DNA Testing
PRINTED RESOURCES
Buckleton, J., Triggs, C. & Walsh, S. (2005). Forensic DNA Evidence Interpretation. Boca Raton, FL: CRC Press.
Bureau of Justice Statistics. (1991). Forensic DNA Analysis: Issues. Washington D.C.: US DOJ.
Burke, T. et al. (eds.) (1991). DNA Fingerprinting : Approaches And Applications. Boston : Birkhauser Verlag.
Conners, E. et al. (1996). Convicted by Juries, Exonerated by Science. Washington D.C.: NIJ.
Gill, P., A. Jeffreys & D. Werrett. (1985). "Forensic Application of DNA Fingerprints" Nature 316:76.
Inman, K. & N. (1997). An Introduction to Forensic DNA Analysis. Boca Raton: CRC Press.
Kelly, J. & P. Wearne. (1998). Tainting Evidence: Inside the Scandals at the FBI Crime Lab. NY: Free Press.
Lee, H. & R. Gaensslen (eds.) (1990). DNA And Other Polymorphisms In Forensic Science. Chicago:Year Book Medical Publishers.
Robertson, J., A. Ross & L. Burgoyne (eds.) (1990). DNA In Forensic Science: Theory, Techniques, And Applications. NY:Ellis Horwood.
Rudin, N. & Inman, K. (2002). An Introduction to Forensic DNA Analysis. Boca Raton, FL: CRC Press.
Sheck, B. (1994). "DNA and Daubert" Cardozo Law Review 15:1959.
Sylvester, J. & J. Stafford. (1991). "Judicial Acceptance of DNA Profiling" FBI Law Enforcement Bulletin, July:29.
Thompson, W. (1995). "Subjective interpretation, laboratory error and the value of forensic DNA evidence" Genetica 96: 153-168.
Tomsey, C., C. Basten, B. Budowle, B. Giles, S. Ermlick & S. Gotwald. (1999). "Use of Combined Frequencies for RFLP and PCR Based Loci in Determining Match Probabilities" Journal of Forensic Science 44(2): 385-88.
Last updated: 02/06/06
Syllabus for JUS 425
MegaLinks in Criminal Justice