One of the giants of the French legal system was found dead near his private island in Brittany on Sunday morning. A suicide note was discovered at his home nearby.

Olivier Metzner, 63, nicknamed the "gangsters' lawyer", was a larger-than-life figure known for his spirited defence of high-profile and controversial defendants including the Panamanian former dictator Manuel Noriega, the "rogue trader" Jérôme Kerviel and Continental Airlines, accused of causing the catastrophic Concorde crash in 2000.

In recent years, he had argued for the former prime minister Dominique de Villepin in the Clearstream scandal, represented rock star Bertrand Cantat when he was accused of killing his actor girlfriend, and argued the case of Françoise Bettencourt-Meyers who tried to have her ailing mother, the the L'Oréal heiress Liliane Bettencourt, declared a ward of court.

Named France's most powerful lawyer by GQ magazine last year, Metzner was often to be seen standing at the top of the Palais de Justice's monumental steps, puffing away on his trademark cigar. Occasionally, he would ignore the no-smoking signs and light up inside, confident that no court official or police officer would dare challenge him.

Outside the courts, where he would pick holes in legal procedure to get his clients off the hook, often in the most blunt of terms and so successfully that Libération described him as the "criminal fraternity's specialist", Metzner was a discreet figure.

Born in 1949 to dairy farmers in Normandy, whose ancestors had fled Prussia in the late 19th century, Metzner described himself as the product of a modest but "rigorous Normand and Protestant education". All three Metzner children escaped the countryside; his brother became a scientist and his sister a teacher in Canada.

He chose law after devouring the works of Kafka and reading a story in his local paper about a shepherd who had been sentenced to death.

"He was from the mountains and incapable of explaining his defence in any understandable language. It made me want to be an interpreter for those who had difficult expressing themselves in front of the court and at the same time explain the justice system to them, because the incomprehension goes both ways," he once said.

After studying in Caen, he headed for Paris, saying two decades in the "damp countryside" was long enough, and a career that was rewarding in every sense. Decades after his first case, in which he successfully defended a thief, he admitted his hourly fee had risen to €450 (£390). His last case, last month, was defending the Swiss petrol group Vitol, accused of breaking the United Nations "food for oil" embargo in Saddam Hussein's Iraq.

Metzner never married and described himself as "leftwing at heart".

In 2010 he bought Boëdic Island in the Morbihan Gulf in Brittany, which he described as a "magnificent, remarkable place". But at the end of last year he announced his intention to sell it, saying he had "more interesting plans". "I am a man of projects," he told AFP in November.

His body was found at about 10am on Sunday floating near the island.