Category Archives: DNA

Arrestee DNA – Supremes Decide

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Arrestee-DNA

 

The FBI’s national DNA database, the Combined DNA Index System Program, includes an Arrestee Index of DNA profiles of people arrested in states where local law allows the collection of samples. The procedure of collecting DNA from arrestees has provoked longstanding debates. The US Supreme Court ended the debates with their June 3, 2013, approval of the controversial practice in a 4-3 decision.

The case Maryland v. King began in 2009 with the arrest of King for first- and second-degree assault charges in a Maryland facility. In compliance with the Maryland DNA Collection Act (MDCA), personnel took a cheek swab from King to generate a DNA profile. After King’s DNA profile matched the profile of DNA recovered during an investigation of an unsolved 2003 rape, King was charged with that crime. At his trial, King tried to suppress the DNA match, arguing that the MDCA was unconstitutional, because it violated the Fourth Amendment. The judge was not persuaded, and King was convicted of rape. The Maryland Court of Appeals set aside the conviction on the grounds that the parts of the law that authorized DNA collection from felony arrestees is unconstitutional. The State of Maryland appealed the decision to the Supreme Court.

The Supremes reversed the Maryland Court of Appeals. Four justices decided the following:

 DNA identification of arrestees is a reasonable search that can be considered part of a routine booking procedure. When officers make an arrest supported by probable cause to hold for a serious offense and they bring the suspect to the station to be detained in custody, taking and analyzing a cheek swab of the arrestee’s DNA is, like fingerprinting and photographing, a legitimate police booking procedure that is reasonable under the Fourth Amendment.

The opinion is worth reading not only for the brief history of methods used to identify criminals, but also for the dissent. As a preview, the dissenting Justice Scalia wrote: “The Court’s assertion that DNA is being taken, not to solve crimes, but to identify those in the State’s custody, taxes the credulity of the credulous.”

 

DNA – Fast

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DNA

 

Those multitasking, gun-toting TV CSIs perform DNA tests at record-breaking speeds. After all, they need to solve a crime in 44 minutes (allowing for commercials). The speed of real DNA analysis is catching up.

IntegenX® (Pleasanton, CA) has introduced its RapidHIT 200, which enables investigators to run a DNA test in a quick 90 minutes. The portable RapidHIT 200 is about the size of a small copy machine, and it analyzes DNA in a cheek swab. The device will allow law enforcement officers to quickly identify genuine suspects and eliminate people unrelated to the criminal activity.

“You’re going to see it in the field more,” said Jay Henry, laboratory director for the Bureau of Forensic Services (Salt Lake City). “The crime lab will be the crime scene. You can find out a lot more at the crime scene itself.”

The IntegenX website provides details about this technology, including a link to a recent Evidence Technology Magazine article highlighting RapidHIT.

 

Snacking with Conviction

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Food behind bars

 

When criminals snack at a crime scene, they leave evidence behind. A bitemark in half-eaten food is one type of evidence. Peckish criminals also leave DNA and fingerprints.

Last week, Ryan Pfeil of the Medford Mail Tribune (Oregon) reported that burglary is a thirsty business. Burglars broke into a house through a garage and stole a flat-screen television, jewelry, and other valuable items. The burglars also took a container of orange juice from the refrigerator, drank from it, and left the container in the garage on their way out. Investigators sent the container to the Oregon State Crime Lab for tests.

Lab techs found DNA and fingerprints on the carton. They also found a match between one DNA sample and a DNA profile in the FBI database. The DNA match led investigators to a 33-year-old man who faces charges of first-degree theft, aggravated theft and burglary.

Around the same time, forensic scientists at the University of Abertay Dunde (Scotland) announced that they recovered latent fingerprints from foods.

“Although there are proven techniques to recover fingerprints from many different surfaces these days, there are some surfaces that remain elusive, such as feathers, human skin, and animal skin,” former crime scene examiner Dennis Gentles explained. “Foods such as fruits and vegetables used to be in that category, because their surfaces vary so much – not just in their color and texture, but in their porosity as well. These factors made recovering fingerprints problematic because some techniques, for example, work on porous surfaces while others only work on non-porous surfaces.”

University scientists overcame the problem by modifying a technique designed to recover fingerprints from the sticky side of adhesive tape. You can learn more about this breakthrough at the Abertay University website.

 

DNA and Killer Twins

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DNA

 

A criminal who has an identical twin poses a problem: Identical twins arise from identical DNA. The microenvironment of a developing embryo affects the formation of fingerprint patterns. As a result, identical twins (who developed in different microenvironments) have different fingerprints. What happens when a savvy criminal does not leave fingerprints at a crime scene?

Barry Starr of QUEST Northern California tackled this question in his posting entitled, “Genetic Sleuthing, or How to Catch the Right Identical Twin Criminal.” Starr highlights a sexual assault case in Marseille, France. Using video evidence and standard DNA analyses, police identified two suspects who are identical twins. Which twin is the guilty one?

DNA can offer one way to distinguish between a set of identical twins. Twins begin life with identical DNA, but DNA changes. One type of change is called an epigenetic change. “Epigenetic” refers to changes in DNA that affect gene activity without altering nucleotide sequences in DNA. Researchers have found different epigenetic markers in the DNA of identical twins. DNA mutations, caused by chemicals and UV light, also cause small changes in DNA. Why didn’t police in Marseille rush to order DNA tests for epigenetic markers and mutations? The cost of one million euros to perform the tests discouraged that approach.

If you’re planning to include a killer twin in your story, peruse the comments to Starr’s article. You’ll find plenty of ideas about how your investigators might tackle the problem.