Category Archives: DNA

Who Are You? – Revisited

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SNPs

 

Several weeks ago, I described research at Israel’s Tel-Hai Academic College, which may enable investigators to create a rough portrait of a person from DNA. In the August/September 2012 issue of Forensic Magazine, Timothy D. Kupferschmid provides background information about this type of technology.

Kupferschmid, executive director of Sorenson Forensics, explains that early attempts at forensic phenotyping (i.e., creating a portrait from DNA) used DNA analysis to determine gender, and to predict hair and eye color. Sorenson Forensics developed a DNA test to predict a person’ genetic ancestry. The test relies upon the observation that, during the course of human history, portions of the DNA of human populations living in geographically isolated regions became slightly distinct from the DNA of human populations in other regions. Certain DNA markers are associated with five populations: Western European, Western Sub-Saharan African, East Asian, Indigenous American, and residents of the Indian Subcontinent. As Kupferschmid emphasizes, the test does not reveal “ethnicity” or “race,” which are social concepts that geneticists consider to be arbitrary and without scientific foundation.

You can find details about this new aid for criminal investigations in Kupferschmid’s article, “Forensic Phenotyping: the 21st Century Composite Sketch.” The investigators of your mystery story will thank you.

Arrestee DNA Law on Trial

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Arrestee-DNA

During the late 1980s, Colorado enacted the first US DNA databank law, a law that required sex offenders to provide a DNA sample to law enforcement officials. This was based on the theory that a person convicted of a sex offense was likely to repeat the crime, and therefore, quick access to a DNA profile could identify a repeat offender. Other states enacted DNA laws, expanding the categories of individuals who must donate a DNA sample. Today, all states require the collection of DNA from sex offenders, and most states collect DNA from felony offenders. Many states obtain DNA from juveniles convicted of certain crimes and from individuals convicted of certain misdemeanors. Some states also require collection of DNA from probationers and parolees.

Taking DNA from persons arrested for certain crimes remains controversial. The federal government and about half of the states have laws that allow DNA sampling before conviction. Courts have ruled on both sides of the issue. In 2006, for example, the Minnesota court of appeals ruled that an individual’s privacy interests trumped the state’s interest in analyzing DNA. The court decided that portions of the state’s DNA law “that direct law-enforcement personnel to take a biological specimen from a person who has been charged but not convicted violate the Fourth Amendment to the United States Constitution and Article I, Section 10 of the Minnesota Constitution.” Other courts have approved arrestee DNA collection laws, and supporters of the laws assert that the laws increase the efficiency of criminal investigations and save lives.

Now, the issue is headed toward the US Supreme Court. The case began in 2009 when Maryland police arrested Alonzo Jay King for first-degree assault. Following Maryland’s DNA Collection Act, personnel at the booking facility collected King’s DNA. Analysis revealed that it matched DNA evidence from a rape committed in 2003. Based on this hit, the State charged and convicted King of first degree rape. He was sentenced to life in prison. King appealed the conviction. The Maryland Court of Appeals, the state’s highest court, overturned King’s conviction, holding that the collection of his DNA violated the Fourth Amendment, because his expectation of privacy outweighed the State’s interests. Maryland appealed the decision to the Supreme Court.

During July 2012, Chief Justice Roberts indicated that the Court will probably take the appeal. He also said that “given the considered analysis of courts on the other side of the split, there is a fair prospect that this Court will reverse the decision below.” Taking arrestee DNA may be here to stay.

Who Are You? (Who, who, who, who)

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Finding DNA

 

Technicians painstakingly extract DNA from a few cells recovered from a crime scene. They duplicate segments of the DNA using the polymerase chain reaction. After analyzing the selected DNA fragments, they upload the results into the FBI’s national DNA database, the Combined DNA Index System (CODIS) Program. The result: No hits. The DNA profile is not in the database. Now what?

Researchers at Israel’s Tel-Hai Academic College may provide an answer with a DNA composite portrait based on connections between genes and external human traits.

“The new development will provide tons of leads,” research team leader Dani Bercovich told news website NoCamels.com. “We’ll know the sex of the offender and be able to estimate his height, age range, color and type of hair, eye color and ethnic background — even whether he is right or left-handed.”

Regardless of whether this technology is realized, it certainly can find a place in a mystery or crime story.

Lab Error Might Have Created False Breakthrough

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DNA molecule unwinding from a chromosome inside the nucleus of a cell. Source: National Human Genome Research Institute.

DNA molecule unwinding from a chromosome inside the nucleus of a cell. Source: National Human Genome Research Institute.

 

On July 10, 2012, The New York Times reported a match between DNA linked to the unsolved 2004 murder of Sarah Fox, a Juilliard student, and DNA recovered from a chain at the site of an Occupy Wall Street protest last March.

Protestors had wrapped the chain around an emergency exit door at a subway station to allow passengers to ride free. A surveillance video revealed people handling the chain, but they wore dark hoods and masks. To find the perpetrators, city officials decided to recover DNA from the chain. That’s when they discovered a match between DNA on the chain and DNA recovered from Sarah Fox’s CD player, which was found near her body.

The news reflects the ability of investigators to extract DNA from skin cells left on doorknobs and other surfaces. These samples are known as “touch DNA.” Recovered weapons are also swabbed for later DNA analysis.

Several surprises quickly followed the news about the DNA match. During the investigation of the 2004 murder, police and the Manhattan district attorney’s office had focused on a construction worker as the primary suspect. They never did find sufficient evidence to charge him. Now, the city reported that the matching DNA does not belong to the prime suspect.

On July 11, The New York Times announced an unexpected development: The DNA match may be due to a lab error. According to an unnamed source, the DNA recovered from skin cells on the student’s CD player and from the chain belong to a Police Department employee who works with the Office of the Chief Medical Examiner.

DNA errors wreak havoc on a criminal investigation. Mystery writers know that the same types of mistakes provide useful plot twists.