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Boston Strangler DNA Case Sheds Light On How Long DNA Lasts & Degrades

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This Feb. 25, 1967, file photo shows self-confessed "Boston Strangler" Albert DeSalvo minutes after his capture in Boston. DeSalvo confessed to the string of 1960s killings but was never convicted. He died in prison in the 1970s. Massachusetts officials said Thursday, July 11, 2013, that DNA technology led to a breakthrough, putting them in a position to formally charge the Boston Strangler with the murder of Mary Sullivan, the last of the his slayings. | Getty

The news that 50-year-old DNA provided a break in the Boston Strangler murder case may have you wondering: just how long does DNA last?

Yesterday, investigators on the Boston Strangler murders, which occurred in the 1960s, said that DNA taken from a blanket at one crime scene was a very close match to that of a family member of Albert DeSalvo, the suspected killer.

The findings thus link DeSalvo to the crime scene. Officials now have permission to exhume the remains of DeSalvo, who died in 1973, to test DNA from his body and confirm the match, according to the New York Times.

DNA degrades over time, and just how long it lasts depends on how well it's preserved. Factors such as exposure to heat, water and sunlight can cause the molecule to degrade faster, according to Slate. The best way to preserve DNA is by freezing it, and sealing it in vacuum-packed container, Slate says.

Last year, researchers estimated that the half-life of DNA — the point at which half the bonds in a DNA molecule backbone would be broken — is 521 years. That means that, under ideal conditions, DNA would last about 6.8 million years, after which all the bonds would be broken. But DNA would not be readable after about 1.5 million years, the researchers said.

The oldest DNA recorded was found in Greenland ice, and estimated to be between 450,000 and 800,000 years old.

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