The ‘Microbial Clock’

Here’s my latest article for Newsweek, “Using the Human Microbiome to Predict Time of Death,” inspired by a seminar visit by Dr. Jessica Metcalf during my time in the Ted Scripps Fellowship for Environmental Journalism at CU Boulder. Read an excerpt below.

Brandon Anderson

Flickr Creative Commons photo by Brandon Anderson.

Using the Microbiome to Predict Time of Death

By Sena Christian

On a Tuesday evening in July 2013, a woman in her 50s was found bound, gagged, stabbed to death and wrapped in a carpet in the driveway of her Honolulu home. The woman’s ex-husband hadn’t heard from her since the two had dinner the Saturday before, and he grew worried, so he went over to her house. No one answered the door and her car was missing, so he flagged down a security guard from a building next door. They investigated and quickly noticed a foul odor emanating from around the back of the house. The police were called in and they soon discovered the decaying body, rolled up in a moldy rug tucked away out of view in the driveway. Then they started piecing together evidence about her murder.

In cases like this, in which the body is found in some state of decomposition, one of the key mysteries is the time line of the crime. Investigators may look at cellphone records to see when the deceased sent her last text message. Or ask colleagues when she left work. They might measure the corpse’s temperature to see how much it has cooled or examine insect infestations in a body found in a shallow grave. But these methods can’t be used in all homicide scenarios, and all have flaws. A body’s temperature, for instance, will cool differently depending on if it’s been left in a sunlit room or submerged in cold water. And the more days that elapse between when someone dies and the body is found, the more difficult deciphering the time of death becomes.

“A lot of estimates for time of death really aren’t scientific at all,” says David Carter, an associate professor of forensic science at Chaminade University of Honolulu. For most deaths that’s perfectly fine, because they’re natural, the result of aging or illness. With homicides, though, that detail can be critical, as detectives use it to substantiate witness testimony and determine a timeline of the crime and validate alibis, excluding people from the suspect list. Investigators may soon have a much better—and more scientific—tool at their disposal to help with all that: the “microbial clock.”

… Read the rest of the article here …

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