Irishman Mike Dwyer (24), who was shot dead in Bolivia last Thursday

A 24-year-old Irishman who was shot dead by Bolivian security forces investigating an alleged assassination plot on the country's president was unarmed and wearing his underwear when he was gunned down.

Mike Dwyer was not involved in any shootout with police as reports initially indicated and there is evidence that Dwyer and two other men were coldly assassinated.

Increasing doubts are emerging about the credibility of the so-called plot to murder President Evo Morales and a wound to Dwyer's chest suggests he was shot at close range. One of his alleged co-conspirators also had his hands bound and weapons which the security forces claim were used by the three dead men date from World War I.

Dwyer, who was from Ballinderry, near Borrisokane in Co Tipperary, told his family that he was working in private security in South America. He had posted photographs and updates from his travels on his Bebo site and friends say that if he was an international hitman and mercenary, he would not be posting personal details on the internet.