Robert Lemieux, a Quebec lawyer who rose to prominence in the 1970s defending members of the Front de libération du Québec (FLQ) following the 1970 October Crisis, died Monday.

A person close to Lemieux who requested anonymity said he died at his home in Sept-Iles, in northeastern Quebec, apparently of natural causes, and was found lying on a sofa in his home. He was 66.

The friend told Canadian Press that Lemieux had been suffering from headaches recently.

The Montreal lawyer garnered fame for defending members of the infamous Chenier cell, part of the FLQ, after the province's labour minister Pierre Laporte was murdered during the October Crisis.

Lemieux defended about 30 members of the organization in court and also worked as a negotiator and spokesman for the group following the kidnapping of British diplomat James Richard Cross.

An ardent sovereigntist, Lemieux was accused at the time of being too chummy with the FLQ, a connection expressed in an interview with CBC host Peter Gzowski just after the kidnapping: "I would even go so far as saying the majority of Quebecers, perhaps of French-speaking Quebecers, think this is a beautiful move, and are glad," he said in the 1970 interview.

He was also seen as a fiery orator who persuaded many people to support French-language rights in Quebec, remembers Jérome Choquette, the province's justice minister during the FLQ crisis. "He emerged as an outspoken person for the FLQ," he told CBC News. "He became a rabble rouser — a very enthusiastic supporter."

Lemieux was eventually sentenced to 2½ years in jail after being charged with contempt of court during the trial of one of his Chenier cell clients. He served about 13 months of that sentence, and also spent time behind bars after the War Measures Act was invoked during the October Crisis.

Lemieux never relinquished the idea that Laporte's death was accidental and not the Chenier cell's fault. "History would acquit us," he said at the time. "We will be more-or-less right in the long term, and that our ideas would triumph."

One-time FLQ member Paul Rose, was sentenced to life in jail for Laporte's murder, called him a great friend. "A great man too," he told CBC's French-language service.

"Someone who held civic rights close to his heart," said Rose, who was granted full parole by the National Parole Board in 1982.

After his time served in jail, Lemieux was rarely seen working in the corridors of the Montreal courthouse.

He relocated to Sept-Iles, on Quebec's lower north shore, and in recent years continued to work on cases involving workers' rights and native issues.

In 2000 he defended jailed biker gang members, including Maurice (Mom) Boucher, the former Quebec Hells Angels boss.

The province's coroner's office will perform an autopsy, but provincial police said there is no sign of foul play.

None of Quebec's three main political parties have commented publicly on his death.

With files from the Canadian Press