Kampala, Uganda (CNN) -- Mourners will gather Friday to say goodbye to a Ugandan gay rights activist who was beaten to death with a hammer in his home near the capital.
Weeping family and friends gathered at the scene as questions lingered over whether David Kato was a victim of homophobia.
Late last year, his name and photo were printed on the cover of a tabloid newspaper that called for gays to be executed. The story, which included a banner that said "Hang Them," reignited anti-gay sentiments and sparked an outcry from gay rights groups worldwide.
Police said initial investigations are focusing on robbery in his rough Mukono neighborhood. Kato's money and some clothes were missing after the attack, authorities said.
But some human rights activists said his death was tied to his campaign.
"I'm very angry ... because everybody who knew David knew he was dynamic. He did not have any trouble. He was just a an activist," said Julius Kaggwa, a human rights advocate in the east African nation. "This to me is a hate crime. Really, to put it bluntly, it is a hate crime."
Arrest warrants have been issued for two suspects, authorities said.
Kato told CNN last year that he feared for his life after the list was released. His lawyer said authorities in his neighborhood near Kampala were aware of his concerns.
"The villagers want to set my house ablaze," he said at the time. "They want to burn my house. ... (They say,) 'Can you go away before my house is burned?'"
Activists urged authorities in the east African nation to investigate the killing. They called on the government to protect homosexuals from violence, and act on threats and hostility toward them.
"David Kato's death is a tragic loss to the human rights community. David had faced the increased threats to Ugandan lesbian, gay, bisexual and transgender people bravely and will be sorely missed," said Maria Burnett, senior Africa researcher at Human Rights Watch.
U.S. President Barack Obama said he was saddened by the death of Kato, whom he called a "powerful advocate for fairness and freedom."
He urged the nation's authorities to investigate and hold those responsible accountable.
Earlier this year, Kato and two activists won a case against the magazine that published the list. The court ruled that media in Uganda are barred from releasing details of known or potential homosexuals in the country.
The editor of the Rolling Stone, the tabloid that published the list, denounced the attacks and said he sympathized with the victim's family.
"When we called for hanging of gay people, we meant ... after they have gone through the legal process," said Giles Muhame. "I did not call for them to be killed in cold blood like he was."
The Rolling Stone tabloid is not affiliated with the U.S. music magazine by the same name.
Homosexuality is illegal in most countries in Africa, where sodomy laws were introduced during colonialism. In Uganda, homosexual acts are punishable by 14 years to life in prison, according to rights activists.
Ugandan lawmakers shelved a controversial "anti-gay" proposal introduced in 2009 that would impose stiff penalties against homosexuality -- including life imprisonment and the death penalty.
CNN's Tom Walsh, Faith Karimi and David McKenzie contributed to this report.