A suicide note was discovered at his home nearby, reports the Guardian newspaper.
Mr Metzner, 63, was well known for his spirited defence of controversial defendants such as Panamanian former dictator Manuel Noriega, the ‘rogue trader’ Jérôme Kerviel and Continental Airlines, accused of causing the catastrophic Concorde crash in 2000.

Most powerful

Mr Metzer, who was named France's most powerful lawyer by GQ magazine last year, also defended former prime minister Dominique de Villepin in the Clearstream scandal and represented rock star Bertrand Cantat who was accused of killing his girlfriend.
According to the report, Mr Metzner was found at around 10am floating near Boëdic Island in the Morbihan Gulf which he had bought in 2010.