US/World

Woman’s DNA Found On Boston Marathon Bomb

Woman's DNA Found on Boston Marathon Bomb
US Officials are investigating a woman's DNA found on one of the bombs.

A woman's DNA was found on at least one of the bombs in the Boston Marathon attacks.

The Wall Street Journal reports that U.S. officials had found evidence of a female's DNA, but were still in the process of determining whether there was woman involved in the deadly attacks. Officials said that there are multiple possible sources, including a store clerk who could have handled the supplies that brothers Tamerlan and Dzhokhar Tsarnaev used to make the bombs, or a piece of a genetic material that might have accidentally gotten onto the bomb from a marathon bystander.

On Monday, FBI agents travelled to Rhode Island to collect the DNA of Katherine Russell, the widow of Tamerlan Tsarnaev. She had been staying with her parents ever since her husband died in a shootout with police on April 19. 

"The FBI is there as part of our ongoing investigation, but we aren't permitted to discuss specific aspects of our case," FBI spokesman Special Agent Jason Pack told USA Today.

Last week, Russell's attorney Amato DeLuca told USA Today that she was "doing everything she can" to assist the investigation.

Russell is among a number of suspects from whom officials are collecting DNA samples.

According to BBC Science, in forensic DNA testing, the DNA is isolated, and then copied millions of times using a method called polymerase chain reaction (PCR), which uses a naturally occurring enzyme to make numerous copies of the DNA, making it easier to analyze.

Once there are a number of copies, the DNA molecules are then split at specific locations and the code on each piece is analyzed, creating a DNA fingerprint. This DNA fingerprint is then compared to another DNA sample. Even if the samples match, there is still a very small chance that they came from different people. To reduce this chance, scientists test between six and ten genetic markers in each sample. By doing this, the chances that two unrelated people have identical profiles becomes less than one in 1,000,000,000.

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