Also in this week's column:

What is a confessing Sam?

Asked by Casey Filocamo of Edmonton, Alberta

"Confessing Sam" is the term in criminal psychology for a person who makes a false confession after a particularly widely publicised crime has taken place.

Some Confessing Sams will admit to just one infamous crime reported in the media. Others will confess to every infamous crime. Confessing Sams will often continue to maintain their guilt long after police rule them out as suspects.

The first genuine Confessing Sam was Robert Hubert. In 1666, the Great Fire of London destroyed 80 per cent of the city. Hubert confessed to having started the fire by throwing a crude fire grenade through an open bakery window. At his trial it was proven that Hubert, a sailor, had not arrived in England until two days after the fire started, was never near the bakery where the fire started, and was so badly crippled that throwing anything was beyond him. If that were not enough, the bakery had no windows.

Nevertheless, as a foreigner, a Frenchman, and a Catholic, Hubert was a perfect scapegoat. Ever maintaining his guilt, Hubert was brought to trial, found guilty, and duly executed by hanging.

The extremes to which some Confessing Sams will go is illustrated by John Hart. In the 1920s, Hart confessed to the Jack the Ripper murders in late nineteenth century London. Although it was pointed out that Hart was only three years old at the time of the first murder, this did not shake his story. He maintained he was Jack the Ripper for the rest of his life.

More than 50 people confessed to having committed the famous and still unsolved Black Dahlia murder in Los Angeles in 1947. None was ever charged.

At least six people have confessed to being the Zodiac Killer. The Zodiac Killer terrorised San Francisco on a murderous rampage beginning in 1968. One of the confessants is a woman - a "Confessing Samantha". The case is still unsolved.

At last count, 20 individuals have confessed to the 1996 murder of child beauty queen Jon Benet Ramsey.

Why does someone become a Confessing Sam? According to forensic psychiatrists, Drs Peter Quintieri of the School of Medicine at Duke University and Kenneth Weiss of the University of Medicine and Dentisty of New Jersey, writing in the Journal of the American Academy of Psychiatry and Law in 2005, there are many reasons why someone will give a non-coerced false confession: mental illness, mental retardation, attention-seeking, publicity-seeking, or a combination of these.

Often a psychiatric disorder, one involving severe guilt feelings completely unrelated to the crime at hand, may provide the motivation.

Researchers ironically note that it is often just as difficult to know whether or not someone is telling the truth when they plead against themselves as when they plead for themselves.

Dr S M Kassin and two colleagues from the Department of Psychology at Williams College in Massachusetts report in the April, 2005 Law and Human Behaviour that when college students and police investigators judged 10 prison inmates confessing to crimes (half the confessions were true, half were false as they were concocted for the study), the students were more accurate than the police in determining who told the truth.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au