As a corpse decomposes, it fidgets for more than a year, researchers found. The discovery could inform crime-scene investigations.

The dead may not always rest in peace, new research shows. For more than a year after death, corpses move around "significantly," and this finding could be important for forensic investigations.

Researchers at an Australia-based decomposition research facility — colloquially known as a "body farm", a term some scientists find disrespectful — made the startling discovery after using time-lapse cameras to film decomposing corpses.

For 17 months, a camera at the Australian Facility for Taphonomic Experimental Research ( AFTER) has been taking overhead images of a corpse every 30 minutes during daylight hours. And for the duration of the research, the corpse has continued to move.

"What we found was that the arms were significantly moving, so that arms that started off down beside the body ended up out to the side of the body," medical scientist Alyson Wilson of Central Queensland University told the Australian Broadcasting Corporation.

Some post-mortem movement was expected in the very early stages of decomposition, she explained, but the fact that it continued for the entire duration of filming was a complete surprise.

"We think the movements relate to the process of decomposition, as the body mummifies and the ligaments dry out," Wilson said.

"This knowledge could be significant in unexplained death investigations."

In fact, it could change how scientists analyze and interpret crime scenes, particularly when human remains have been undiscovered for some time.

Until now, unless there was evidence that a body had been moved — either by animals or people — forensic scientists generally would assume that the position of a discovered body is the position at time of death.

Since Wilson's research is the first use of a time-lapse camera to study human decomposition, this is also the first evidence that assumptions about a body's position at the time of death may not be true.

A paper describing the discovery that corpses are rather more lively than expected has yet to be published, but this research follows up on Wilson's previous work, which was published in the journal Forensic Science International: Synergy earlier this year.

In that study, Wilson and her colleagues used a time-lapse camera to track the decomposition of a corpse for six months. The researchers compared the images to a system of classifying different levels of body decomposition in order to determine how long the person had been dead for — which is called the post-mortem interval.

The system neatly matched the time-lapse photographs, adding to the system's validity as a forensic tool; additionally, the team's results validated the usefulness of time-lapse cameras in forensic research.

Based on these findings, it appears that if enough corpses are studied with long-term time-lapse photography to generate statistical data on bodies' movements after death, that knowledge could be used to analyze crime scenes with greater accuracy in the future.

Such a database would provide information on the ways in which people are likely to move, which in turn could allow forensic scientists to reconstruct the position the body was in at the time of death. In turn, that could help investigators determine out what happened.