KAMPALA (Reuters) - A Ugandan gay rights activist murdered after his photo was printed on the cover of a newspaper that called for gays to be executed was likely killed during a robbery, police said on Thursday.

David Kato was one of three people featured in Uganda’s Rolling Stone newspaper in October who won an injunction this month barring it from continuing its anti-gay campaign that had pictured gays under the headline: “Hang Them.”

Kato said he had received death threats since Rolling Stone’s publication.

The U.S. State Department’s top diplomat for Africa, Johnnie Carson, expressed shock at Kato’s murder, which followed strong U.S. pressure on Uganda’s leadership to tone down anti-gay political rhetoric.

“We are horrified and saddened by the murder of prominent human rights activist David Kato in Uganda yesterday afternoon,” Carson wrote in a message on Twitter.

The murder sparked worldwide condemnation and fast became one of the top 10 topics on the social media website Twitter.

Kato was attacked at home and died on the way to hospital. Police said he had been bludgeoned to death with a hammer.

Police told a news conference in the capital Kampala that one man, Arnold Senoga, had been arrested in connection with the killing and that they were looking for another man, Nsubuga Enock, who had been staying with Kato after the activist bailed him out of prison on Monday.

“His homosexuality has not come up as an issue in the preliminary investigation,” police spokeswoman, Judith Nabakooba, told Reuters.

“At the moment, we think theft is the most likely motive. Nsubuga Enock, who had been staying with Kato, was well-known for committing robberies and had almost been lynched in the area before.”

Nabakooba said items were missing from Kato’s home, including a briefcase, and that neighbors had seen Enock leave the house dressed in the activist’s clothes.

“We are now trying to establish what relationship Kato had with Enock, whether or not they were relatives and why Kato posted his bail,” Nabakooba said.

“HANGED, NOT STONED”

Gay rights campaigner, Pepe Julian Onziema, who worked with Kato at rights group, Sexual Minorities Uganda, told Reuters she suspected he was killed for being gay.

“David had faced so many threats in his area that he didn’t feel safe anymore,” Pepe said. “I don’t know if the police are aware but they should investigate that before ruling out homophobia. He was too frightened to leave his house.”

Rights groups and gay campaigners were quick to condemn the attack on Thursday with many calling on Uganda to quash a tabled parliamentary bill that proposes a death penalty for gays who are “repeat offenders.”

The bill was quietly shelved after international pressure, but rights groups fear it may be passed after a February presidential election that Museveni is expected to win.

“This savage killing will, I hope, finally prompt Uganda’s political, religious and media leaders to cease their homophobic witch-hunts,” British gay rights campaigner Peter Tatchell said.

Homosexuality is taboo in many African nations, including Uganda. It is illegal in 37 countries on the continent and activists say few Africans are openly gay, fearing imprisonment, violence and loss of jobs.

Rolling Stone published 29 photographs with names and, in some cases, addresses before the High Court ordered it to stop on grounds of privacy.

Giles Muhame, the 22-year-old editor of the newspaper, told Reuters he condemned the murder and that the paper had not wanted gays to be attacked.

“If he has been murdered, that’s bad and we pray for his soul,” Muhame said.

“There has been a lot of crime, it may not be because he is gay. We want the government to hang people who promote homosexuality, not for the public to attack them. We said they should be hanged, not stoned or attacked.”