Prominent Cameroonian gay rights activist and journalist Eric Lembembe has been killed in the capital, Yaounde, a rights group says.
Mr Lembembe's neck and feet appeared to have been broken and his face, hands, and feet burned with an iron, Human Rights Watch (HRW) said.
The cause of the killing is not known, but Mr Lembembe is the latest activist to be targeted in Cameroon, it added.
Homosexual acts are illegal in socially conservative Cameroon.
"The police should not rest until the perpetrators of this horrific crime are brought to justice. President Biya should break his silence on the wave of homophobic violence in Cameroon and publicly condemn this brutal attack," said HRW researcher Neela Ghoshal in a statement.
Mr Lembembe, the executive director of the Cameroonian Foundation for Aids, was a courageous activist who campaigned for equal rights, despite severe discrimination and violence, HRW said.
His friends discovered his body at his home in Yaounde on Monday, after being unable to reach him by phone for two days, it said.
HRW said that in other suspected homophobic attacks:
the headquarters of Alternatives-Cameroun, a non-governmental organisation which provides HIV services, was burned down on 26 June in the commercial capital, Douala
the Yaounde office of human rights lawyer Michel Togue, who represents clients charged with same-sex conduct, was burgled and his legal files and laptop stolen
Mr Togue and Alice Nkom, another lawyer who represents gay and lesbian people, have received repeated death threats by email and SMS, including threats to kill their children.
Cameroonian police have not apprehended a single suspect, although activists have reported all the incidents, HRW said.
In December, a Cameroon appeals court upheld the sentencing to 36 months in prison of Roger Jean-Claude Mbede under anti-gay legislation.
His lawyer said he was sentenced simply for sending a text to someone to say he loved him.
In January, the appeals court overturned the conviction of two men jailed in 2011 for homosexual acts.
Homosexual acts are illegal in many African countries - including Uganda, which is considering imposing harsher penalties.
The US and European Union (EU) have threatened to cut aid to countries that fail to repeal legislation that outlaws homosexual acts.