A Church of Scientology-backed organisation has distributed free DVDs about anti-depressant drugs in the area where killer Shane Clancy lived.

The group, called the Citizens Commission on Human Rights (CCHR), has given out copies of a documentary to residents in the Dalkey area, just weeks after the tragic murder-suicide in Bray, Co Wicklow.

Reports have indicated that gardai are investigating whether Shane, who murdered Seb Creane (22) before killing himself, may have misused anti-depressants that had been prescribed for him a week before the tragic night.

The DVD, which is also available online, details interviews with psychiatrists, psychologists, and journalists, exposing what it calls "psychiatric violations of human rights."

Making A Killing: The Untold Story Of Psychotropic Drugging is made in the US, but has been distributed in Ireland by a branch of the CCHR.

The DVD's tagline says it tells the "story of big-money drugs that fuel a $330bn psychiatric industry, without a single cure."

But since its release, one professional involved with the DVD has distanced himself from the CCHR.

Professor Howard Brody said that he believes anything produced by this organisation requires independent confirmation.

He said: "I regret very much allowing myself to have become involved in this project and would like it to be known that I disown and disapprove of the final product and the way that it has been disseminated."

One expert witness at the Columbine shootings has said that Shane Clancy may have reacted negatively to anti-depressants, affecting his state of mind at the time of the attack.

The executive director of the International Coalition for Drug Awareness, Dr Ann Tracy, believes that Shane may have lacked vital liver function necessary to metabolise anti-depressants.

The US-based doctor pointed out that if levels of anti-depressant in Shane's blood were high, it does not necessarily mean that he was taking more than he should have.

She said: "It can mean that he, like seven to 10pc of the population, lacked the liver function necessary to break down the drug causing it to build to toxic levels."

CCHR spokesman Brian Daniels said the DVD was intended to "let the public know what is going on."

He said: "There are undiagnosed physical conditions which can manifest as mental illness."

Belfast Telegraph