Rwanda's former intelligence chief has turned up dead in a Johannesburg hotel room.

Details are few, but South African police say they've begun a murder investigation. They found a rope and a bloody towel in a safe in the Michelangelo Towers hotel room of Patrick Karegeya and the former spymaster's body showed signs of possible strangulation.

Karegeya was a fierce critic of Rwanda's current president, Paul Kagame. Government dissidents are calling the killing a political assassination.

But the Rwandan government is denying involvement and New Yorker staff writer Philip Gourevitch says it's too early to point a finger of blame in the killing.

"What can be said at this point is there's a consistent pattern of people who were insiders of the government and have very intense fallings out with the government of Paul Kagame going into exile and going into absolute opposition," Gourevitch says. "It's not a party that tolerates dissent internally and when they go into opposition they start to call for the overthrow of that government. And there have been either attacks, alleged threats, warnings of various kinds."