KAMPALA, Uganda (AP) — A prominent Ugandan gay rights activist whose picture was published by an anti-gay newspaper next to the words "Hang Them" was bludgeoned to death. Police said Thursday his sexual orientation had nothing to do with the killing and that one "robber" had been arrested.

Activists were outraged over the death of David Kato, an advocacy officer for the gay rights group Sexual Minorities Uganda. His slaying comes after a year of stepped up threats against gays in Uganda, where a controversial bill has proposed the death penalty for some homosexual acts.

Kato, who had received multiple threats, was found with serious wounds to his head caused by an attack with a hammer at his home late Wednesday in Uganda's capital, Kampala. Kato later died on the way to the hospital.

Our thoughts and prayers are with his family, friends, and colleagues," U.S. Secretary of State Hillary Rodham Clinton said. "We urge Ugandan authorities to quickly and thoroughly investigate and prosecute those responsible for this heinous act. David Kato tirelessly devoted himself to improving the lives of others.

Human Rights Watch called for an urgent investigation, saying that Kato's work as a prominent gay rights campaigner had previously seen him face threats to his personal safety.

David Kato's death is a tragic loss to the human rights community," said Maria Burnett, senior Africa researcher at HRW. "David had faced the increased threats ... bravely and will be sorely missed.

A Ugandan tabloid newspaper called Rolling Stone listed a number of men they said were homosexuals last year, including Kato. Kato's picture was published on the front page, along with his name and a headline that said "Hang Them.

Kato and two other gay activists sued Rolling Stone over claims that it had violated their constitutional rights to privacy and won the case earlier this month. A judge issued an injunction banning the publication of the identities and personal details of alleged homosexuals.

A police spokesman, Vincent Sekatte, said Kato was killed by robbers who have so far killed more than 10 people in that area in the past two months. He said there was no indication the death was connected to any anti-homosexual sentiment. Kato was hit by a hammer that has been recovered by police, Sekatte said.

Police arrested one suspect, a driver for Kato, Sekatte said. A second suspect is being hunted. That suspect had been hired as a house helper and had recently been released from prison, Sekatte said.

Kato's lawyer told The Associated Press on Thursday that his client had become noticeably more worried about his safety in the wake of the Rolling Stone publication.

He was conscious that something could happen," said John Francis Onyango.

Family, friends and neighbors gathered to mourn at Kato's house on Thursday. Several women lay on the floor of the living room. The room where he had been killed was closed off by the police. A funeral is planned for Friday.

I feel very lonely," said John Mulumba Wasswa, Kato's older twin brother. "My brother was a very brave person, very courageous.

Homosexuality is illegal in Uganda and gay men and women face regular harassment. The controversial bill introduced in 2009 and still before the country's parliament would see the death penalty introduced for certain homosexual acts. The bill prompted international condemnation and hasn't come up for a vote

Human Rights Watch called on the Ugandan government to offer gay people in the country sufficient protection.

In a statement, the group said that witnesses had told police that Kato was hit twice on the head by an unknown assailant who had been spotted entering his property. The assailant was then seen leaving by vehicle, the statement said.

Frank Mugisha, the chairman of Sexual Minorities Uganda, said he has asked religious and political leaders and media outlets to stop demonizing sexual minorities in Uganda.

Across the entire country, straight, lesbian, gay, bisexual, transgender and intersex Ugandans mourn the loss of David, a dear friend, colleague, teacher, family member and human rights defender," said Mugisha.

The introduction of the anti-homosexual bill in 2009 followed a conference in Kampala that was attended by American activists who consider same-gender relationships sinful. The U.S. evangelicals believe gays and lesbians can become heterosexual through prayer and counseling. Some gay Ugandans still resent that American intervention.

David's death is a result of the hatred planted in Uganda by U.S evangelicals in 2009," said Val Kalende, a Ugandan gay rights activist. "The Ugandan government and the so-called U.S evangelicals must take responsibility for David's blood.

___

Matthew Lee in Washington contributed to this report.