Photo credit: Illustration by Louise Zergaeng Pomeroy
By Peter Andrey Smith
The bright aseptic room smelled of Pine-Sol and bleach and overripe Camembert. A white-bearded man lay on a stainless-steel examination table, his face angled toward the skylight and the cold, cloudless morning. An investigator read from his clipboard: 61-year-old white male discharged from a Detroit hospital last night was found at home, shirtless, in a wheelchair, a .38-caliber handgun in his right hand. On his chest was a burn that appeared to be an exact match of the gun’s barrel. Carl Schmidt, the medical examiner, wiped the contact wound with a wet sponge.
“If we’re lucky, it exited,” he said.
Two technicians hefted the body onto its side.
“And . . . let’s look at the other side.”
The skin was mottled where the blood had begun to settle, but his back had no open wounds.
“We’re going to have to extract the bullet.” Schmidt paused. “Next.”
He had seven more bodies to inspect. By his account, it had been a typical night. Schmidt and his team — a pathology fellow, a medical student and three autopsy technicians — moved over to examine two pedestrian fatalities struck down when a vehicle jumped a curb. Schmidt felt around their skulls for fractures. Another man with a history of cardiovascular disease had been found at the bottom of a stairwell; and an elderly woman, her body bag marked “decomp,” had lain alone for several days, undiscovered. The most perplexing case was a 27-year-old woman who was found dead in a city park with a USB phone-charging cable tied around her arm, the victim of an overdose. “She was out shooting drugs in a park on a Saturday night with a frost warning?” Schmidt asked, a roundabout way of suggesting she might have overdosed before being dumped outside. Though she was unidentified, she had one thing in common with the other bodies: The exact time of death was unknown and practically unknowable.
Schmidt, a soft-featured, 58-year-old pathologist (or, as he put it, “a balding, fat white guy”), has served as the chief medical examiner for Wayne County, which includes Detroit, one of the nation’s busiest morgues, for 13 years. When I visited in October, his office had handled more than 2,800 bodies that year, 1,900 of which involved autopsies. Autopsy reports provide a basis for legal and criminal investigations, and limitations in their findings contribute to why about a third of murders nationwide never lead to an arrest.
That Sunday morning, Schmidt snapped on two pairs of purple gloves and pulled on a Tyvek suit. Before he autopsied one pedestrian, Schmidt swirled a sterile cotton-tipped applicator in an ear of the victim, snapping off the tip into a plastic container, then swabbed her nose, mouth and belly button. An autopsy technician cut a quarter sphere into her skull with an electric saw, pulled off the cap and rolled another swab over the cross-section of the bone. “See right there?” Schmidt said. “The reason we do this is the head is probably the most sterile place of the body.” He pointed to the dark fissure separating the brain’s hemispheres, a region he expected to serve as a negative control for the experimental analysis. “This is ideal because the head is far away from the viscera, which are teeming with bugs.”
No problem in forensic science has been investigated more, and understood less, than the post-mortem interval. Medical investigators calculate the interval between death and the discovery of a body using three cardinal measurements: temperature (algor mortis), stiffness (rigor mortis) and the settling of blood (livor mortis). These factors vary depending on a person’s distribution of visceral fat, as well as their clothing, the ambient air temperature and other factors. After two days or so, though, these observations are no longer trustworthy. Schmidt keeps a copy of a statistical opus on post-mortem intervals, in which Claus Henssge and his co-authors warn against extrapolating much beyond 48 hours, but he takes an even more pessimistic view. “Post-mortem interval is one of the most pseudoscientific bits of information out there that, and I hate to use this, will never die.”
Medical examiners can often deduce cause of death based on an autopsy, but the exact time of death is hard to determine. At best, this evidence comes from an attending physician or, lacking that, an eyewitness. “But let’s say that a body was dumped in an alley or one of Detroit’s many empty lots,” Schmidt said. “And that’s all you know about the case. Let’s say it’s August and it’s 90 degrees. And the body is flaccid and lividity is fixed. So, has that body been there for less than 24 hours or more than 24 hours? The answer is: Who knows?”
Which was why Schmidt had teamed up with a group of scientists — Heather Jordan, a microbiologist in Mississippi; and Eric Benbow and Jennifer Pechal, two entomologists in Michigan — to systematically swab bodies during routine death investigations. They hoped to gather testimony from an unusual set of witnesses: the microbes that live after we die.
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