Blood Alcohol Scores After Death Can Be “False Positive” Up To 0.20

In handling wrongful death and life insurance claims for clients, I learned years ago that blood alcohol tests after a person dies may not be reliable. Due to postmortem fermentation when a body is not kept cool after death, there can be “false positive” blood alcohol reports up to 0.20 grams/% — 2 ½ times the legal limit of 0.08 for drivers and boaters in Georgia.

Years ago, I was hired by the widow of a retired Army officer who drowned on a fishing trip. A life insurance policy excluded coverage if the insured was intoxicated at the time of death. An autopsy by the state medical examiner reported blood alcohol of 0.20 gr/%. But both the widow and her late husband’s fishing partner swore he had had nothing to drink. At first we thought the county coroner, on whose property the drowning occurred, might have messed with blood samples.

When I contacted an independent pathologist, I learned that fermentation could have produced the blood alcohol score. The body had been retrieved from a lake in south Georgia on a hot August day, laid out in the sun for a while, and then was transported by hearse in uncertain temperature conditions on an hours-long drive to the state medical examiner’s office in Atlanta.

That was enough for fermentation to occur. With that knowledge, we won.

Why is that?

As discussed in a recent article by forensic scientist Jim Wigmore, over half of postmortem blood is not sterile, and contains bacteria, yeast or fungi. In addition, postmortem blood sugar (glucose) concentration can be 7 to 10 times greater than blood before death.

Fermentation is the formation of alcohol from sugar.  Yeasts can convert 100 milligrams of glucose into approximately 40 to 50 milligrams of alcohol.  Bacteria and fungi generally can convert 100 milligrams of sugar into 10 – 20 milligrams of alcohol.

During fermentation other volatile compounds such as acetaldehyde and n-propanol are produced and may assist in the determination of elevated blood alcohol scores due to fermentation or putrefaction.

It has been well established for many years that:

  1. Blood alcohol levels at autopsy are valid up to 48 hours after death when solid protocols are observed in the collection and storage of samples.
  2. Alcohol levels in samples of blood taken from the intact heart are as significant as levels of blood from the femoral veins.
  3.  False blood alcohol levels greater than 0.200% can be generated in autopsy blood samples which are not correctly stored.
  4.  High blood alcohol levels may develop during putrefaction and levels up to 0.200% do not necessarily indicate that alcohol was imbibed before death.
  5. Significant false high blood alcohol levels do not develop during incineration in absence of putrefaction.

We have to be alert to this scientific knowledge in handling cases where any person after death is accused of having been drunk at the time of death.


Ken Shigley is a board certified trial lawyer based in Atlanta. He is a past president of the State Bar of Georgia, chair-elect of the American Association for Justice Motor Vehicle, Highway & Premises Liability Section, and a Certified Civil Trial Advocate of the National Board of Trial Advocacy.