29 November 2012 Last updated at 13:01 ET

LSD trial man Frank Olson 'killed' by CIA, sons say

Frank Olson's sons claim their father was killed by the CIA

The sons of a CIA scientist who unwittingly took LSD and fell to his death in 1953 have sued the government, saying the CIA killed their father.

Eric and Nils Olson claim their father, Frank Olson, was pushed out of a 13th-floor hotel window, days after he was given LSD in a mind-control experiment.

They claim the bio-weapons expert had doubts after seeing interrogations with biological tools he had helped develop.

The intelligence agency has always maintained Olson jumped to his death.

The lawsuit was filed in federal court in Washington DC on Wednesday.

Extreme interrogation

The Olson family received a compensation package from the government during reforms of the intelligence agency in the 1970s, after the CIA acknowledged that Olson had been given LSD nine days before his death.

The agency said at the time that Olson died after leaping from a Manhattan hotel window, but his family believes he was killed by the CIA to keep secret information about disturbing operations he had uncovered.

In 1953 Olson travelled to Europe and saw biological and chemical weapons research facilities there.

The lawsuit alleges that Olson witnessed extreme interrogations there, some resulting in deaths, in which the CIA had used biological agents he helped develop.

Olson had been a bioweapons expert based at a military biological weapons research centre in Fort Detrick, Maryland.