Russian-Jewish oligarch and Kremlin critic Boris Berezovsky was hanged, a post-mortem examination found.
There was no sign of a violent struggle, the Independent reported citing Thames Valley Police. Further tests will take several weeks, the newspaper reported.
Berezovsky's body was found March 24 in the bathroom of his home in the London are. Berezovsky, 67, once the richest man in Russia, fled to Britain about 10 years ago following a falling-out with Russian President Vladimir Putin amid fraud charges that Berezovsky said were politically motivated.
The Moscow native, the son of a Jewish father and a mother with Jewish roots, immigrated to Israel in 1993 but later renounced his Israeli citizenship, according to the Israeli news website Walla.
Berezovsky became a strident and frequent critic of Putin, accusing the leader of ushering in a dictatorship.
He accumulated his wealth in the years following the collapse of Soviet Russia by acquiring local firms, including oil companies and television stations, rising to prominence during the term of Boris Yeltsin in the 1990s. Russian media reported recently that Berezovsky had suffered heavy financial losses.