Former British mercenary Simon Mann, who was part of an attempted coup in Equatorial Guinea in 2004, has died of a heart attack while exercising, the UK’s BBC reported on Friday.

Educated at Eton, Britain’s top private school, the ex-special forces officer was arrested in Zimbabwe along with 70 other mercenaries en route to Equatorial Guinea aboard a plane.

Extradited to Equatorial Guinea, he was sentenced in July 2008 for conspiring to topple President Teodoro Obiang Nguema Mbasogo. He was pardoned on health grounds, having served just over one year of a 34-year sentence.

During his trial, Mann portrayed himself as a pawn of international businessmen, he said were trying to seize power and named the son of former British Prime Minister Margaret Thatcher as being involved — an allegation Mark Thatcher has denied.

The BBC said Mann died aged 72 of a heart attack.