The DNA Double Helix
On the DNA double helix, guanine is always paired with cytosine, and adenine is paired with thymine, this giving the familiar G-C and A-T configurations.
Readers with a long memory and a taste for sci-fi films will probably recall that in 1997 a film was released that intriguingly, and cleverly, used the base-pair codes to fashion the film's title: GATTACA.
In addition to its sci-fi credentials, GATTACA was also a mystery-thriller that was well-received by the critics, even if it appears to have been a flop at the box office. The estimable Roger Ebert declared the film to be "one of the smartest and most provocative of science fiction films, a thriller with ideas." The scientific community was rather less impressed, although the molecular biologist Lee. M. Silver stated in a review in a scientific journal that "GATTACA is a film that all geneticists should see if for no other reason than to understand the perception of our trade held by so many of the public-at-large". I don't think that qualifies as a real endorsement of the film. I also don't think the "public-at-large" is a reliable source of opinion on science in general.
Anyone who reads mystery fiction, and especially anyone who reads technical material, will be aware that "DNA profiling" - originally, and inaccurately, known as "DNA fingerprinting" - is a standard and invaluable technology for solving crimes, especially crimes of violence such as murder and rape. DNA profiling is based on the fact that every person's DNA profile is unique; only identical (monozygotic) twins have identical DNA profiles. Hence the technology's value in identifying individuals on the basis of their DNA profile, through DNA extracted from bodily fluids: blood, semen, saliva, etc.; or from skin cells harvested from a victim's fingernail scrapings; or from strands of hair, as long as the hair root is present.
What is, I believe, somewhat less well-understood, is that DNA profiling is especially valuable in the exoneration of innocent people who have been incorrectly arrested and charged.
Herewith a quick perusal of some of the landmark cases in DNA profiling and forensic DNA use and application in crime detection.
- In the 1950s, Anna Anderson claimed that she was Grand Duchess Anastasia of Russia. In the 1980s, after her death, samples of her tissue that had been stored at a Charlottesville, Virginia hospital following a medical procedure were tested using DNA profiling, and showed that she bore no relation to the Romanov Royal Family.
- In 1986, Richard Buckland was exonerated, despite having admitted to the rape and murder of a teenager near Leicester, the city where DNA profiling was first discovered. This was the first use of DNA "fingerprinting" in a criminal investigation.
- In 1987, in the same case as Buckland, British baker Colin Pitchfork was the first criminal caught and convicted using DNA profiling.
- In 1987, DNA "fingerprinting" was used in criminal court for the first time in the trial of a man accused of unlawful intercourse with a mentally handicapped 14-year-old female who gave birth to a baby.
- In 1987, Florida rapist Tommie Lee Andrews was the first person in the United States to be convicted as a result of DNA evidence, for raping a woman during a burglary; he was convicted on November 6, 1987, and sentenced to 22 years in prison.
- In 1988, Timothy Wilson Spencer was the first man in Virginia to be sentenced to death through DNA testing, for several rape and murder charges. He was dubbed "The South Side Strangler" because he killed victims on the south side of Richmond, Virginia. He was later charged with rape and first-degree murder and was sentenced to death. He was executed on April 27, 1994. Equally significant, David Vasquez, initially convicted of one of Spencer's crimes, became the first man in exonerated based on DNA evidence.
- In 1989, a Chicago man, Gary Dotson was the first person whose conviction was overturned using forensic DNA evidence.
- In 1991, Allan Legere, a serial killer and arsonist, was the first Canadian to be convicted as a result of DNA evidence, for four murders he had committed while an escaped prisoner in 1989. During his trial, his defense argued, unsuccessfully, that the relatively shallow gene pool of the region could lead to false positives.
- In 1992, DNA evidence was used to prove that Nazi doctor Josef Mengele was buried in Brazil under the name Wolfgang Gerhard.
- In 1992, DNA from a palo verde tree was used to convict Mark Alan Bogan of murder. DNA from seed pods of a tree at the crime scene was found to match that of seed pods found in Bogan's truck. This is the first instance of plant DNA admitted in a criminal case.
- In 1993, Kirk Bloodsworth was the first person to have been convicted of murder and sentenced to death, whose conviction was overturned using DNA evidence. The actual murderer, Kimberly Shay Ruffner, identified by forensic DNA technology, eventually pled guilty to the crime. Bloodsworth was released from prison.
Maryland v. King - The Supreme Court Decision
If you've been paying attention to the news lately, you will know that the United States Supreme Court recently brought down a landmark ruling on forensic DNA evidence. The ruling stems from the case of Alonzo J. King, Jr., who was arrested in 2009 on assault charges. When he was booked, the police took a sample of his DNA using a cheek swab. (The use of swabs from the inside of a person's cheek, which yields cells and their DNA, is one of the standard procedures.) The police did not have a warrant to do the swab, or have probable cause to think it would link King to any crime. However, King's DNA profile matched DNA evidence from a rape in 2003, and he was eventually convicted of that crime.
In 2012, Maryland's highest court struck down the state law that allows DNA collection from people who have been charged but not yet convicted, because, they said, it violates the U.S. Fourth Amendment prohibition against unreasonable searches. The U.S. Supreme Court's decision, in a 5-to-4 vote, the narrowest possible verdict, overturned the ruling and upheld the Maryland law.
The Supreme Court's decision saw an interesting pattern of alliances. Three "liberal" justices, Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan, were joined by one of the most conservative justices, Antonin Scalia, in opposing the decision. Scalia believes that the Fourth Amendment clearly prohibits the use of cheek swabs in this way. Justice Anthony Kennedy, writing for the majority, stated that collecting DNA through cheek swabs, or any other procedure, is like fingerprinting, and is a legitimate part of the police booking procedure to identify a suspect.
The ruling is controversial. On June 3rd, the New York Times published an editorial damning the decision. On the same day, two eminent lawyers, Akhil Reed Amar and Neal K. Katyal, argued in an op-ed piece in the Times that the Supreme Court was correct in its decision and, moreover, that Justice Scalia (and by inference, the Times's Editorial Board) had misinterpreted the Fourth Amendment's meaning. It's fairly certain that the issue will remain controversial for some time.
When forensic DNA profiling first began to used back in the late 1980s, it was immediately controversial, with proponents and opponents lining up to argue the pros and cons. I think it is safe to say, though, that on the whole, the technology has proven itself. I am not aware that anyone has been wrongly convicted using the technology. I am also aware that a significant number of wrongly-convicted persons have been exonerated using the technology. The argument that is going on now, with this latest Supreme Court decision, is not that Alonzo J. King, Jr. was wrongly convicted of rape; it's agreed that he was in fact guilty, and fairly sentenced. The argument is over the process that identified him as the assailant in a vicious crime.
Most readers are probably familiar with "Blackstone's formulation" - from Sir William Blackstone, an English jurist and judge, in 1765 - that It is better that ten guilty persons escape than that one innocent suffer. History records that Benjamin Franklin went even farther than that, raising the number to 100 guilty persons from ten. There are of course dissenting opinions on that also.
I will leave the discussion to the lawyers and ethicists, while at the same time declaring my own opinion that forensic DNA technology has done far more good than harm, through delivering the wrongly-convicted from incarceration, while at the same time putting a lot of nasty people behind bars.
I will even go so far as to declare that I believe that, technology and budgets permitting, everyone should be fingerprinted and DNA-profiled shortly after birth. I suspect that some people will be appalled at the suggestion, and will cite Orwell's 1984 - recently back on the best-seller lists, by the way - and if such a policy were adopted, we would hear a great deal about Big Brother. Debate is good. I invite dissenting opinions. I will look forward to reading them.
An that's - 30 - for this outing.