Hand of Guanajuato mummy. Due to weather and soil conditions, bodies tend to dehydrate and mummify in the city of Guanajuato, Mexico. Unclaimed bodies often end up for public exhibit. (Credit: Tomas Castelazo via Wikimedia Commons, CC BY-SA 2.5

A woman fell from a bridge to her death in August 2004—and was found about a month and a half later. The remains of a 57-year-old man were found on a mattress in his apartment, still in a sweater vest and jogging pants, in April 2011—with a pileup of mail outside his door extending back to the previous December. And the body of a pregnant young woman with blunt trauma to skull was found stuffed in a steel drum in September 1999—later determined to be 30 years after she was murdered.

All share one commonality: in death, their remains became mummified through a variety of factors in the South of France.

A survey of 20 bodies cataloged by medicolegal death investigators in the region around Nice found that extensive mummification can happen in a variety of environments in a matter of weeks, according to the new paper in Forensic Science International.

The quickest “extensive” case of mummification cataloged was about three weeks in a warm and dry apartment.

The remains were all subject to death investigations between 2002 and 2016. Thirty-five cases were originally studied—but 15 of them were discarded because there were extreme difficulties in pinpointing the time of death for the study.

Each of the remains had to have “extensive” mummification over the bodies, meaning at least 50 percent of the outside of the body was desiccated.

The forensic problem: time of death can be virtually impossible to pinpoint, and cause of death isn’t that much easier, let alone the manner of death, according to the authors, from the Université Côte d'Azur.

For the 20 cases surveyed, investigators were able to narrow down the time of death based on the time the person was last seen or other contextual evidence, like mail piling up outside an apartment.

Fifteen of the mummification cases were found indoors: 13 in apartments, one in a garage, and another inside a boat. But five were found in the outdoors; that included people who disappeared not only in the warm summertime—but also those who had disappeared in the autumn and winter.

The complex combination of decomposition and mummification shows there is a dynamic not totally understood in the natural processes of the dead.

“The process of mummification ideally requires a sealed environment so no flies can lay eggs on the cadaver, leading to the decomposition of the body,” they write. “Nevertheless, a combination of mummification and decomposition was observed in half our cases.

“In our opinion there is a natural competition between fly-led decomposition and mummification that explains that some bodies simultaneously present both processes, with mummification sometimes becoming preponderant during the process,” they add.

Among the other findings:

  • Starting weight—at the time of death—could be key to the process. Eight of the 20 deceased were thin or emaciated when they took their last breath, including five suffering from severe psychiatric disorders.
  • Insect access to the body is key. Hermetically sealed locations are most likely to foster mummification. However, certain metals, chemical products like gasoline or hydrochloric acid, or certain narcotics can also keep away the critters. On the other hand, codeine and amphetamines apparently stimulate them.
  • “Wet” mummification—called corification—is possible in certain places. This shows up as mummification on the outside, and decomposition of the viscera within, according to the findings.
  • Identification of mummies means fingerprints are no longer possible—but tattoos, teeth and DNA remaining can still allow positive conclusions.
  • Only three of the 20 cases resulted in cause of death determination. One was from a digestive hemorrhage, one from a femoral neck bone fracture that was clearly not healed—and the massive combined trauma of the woman who fell from the bridge and mummified on the ground.
  • At least a month and a half was required to reach a level of “head to toe mummification,” they found.

Overall, the mummification cases are not exceptionally “rare,” they conclude—since at least a handful are documented in and around Nice each year, they wrote.

According to the textbook Practical Homicide Investigation by Vernon Geberth, the key to mummification is not only heat and relative aridity—there is also commonly a constant circulation of enough dry air allowing body fluids to rapidly dry out, creating the preserved remains.