Two Bulgarians were detained on Saturday for the murder of a 44-year old U.S. citizen, who police said was under investigation for child pornography.
Police said the two boys, aged 17 and 22, confessed to the murder and led them to a site near Sofia, where the victim's body was found dumped in a well late on Saturday.
Police said they have photos of a sexual nature of the two with the murdered man.
"They made full confessions. The two said they had battered him with sticks. He had been still alive when they had thrown him in the well," Interior Ministry Chief Secretary Boiko Borissov told Reuters.
Police said they were searching for another 22-year-old man in connection with the murder of the American, whose name was not disclosed.
Borissov said the victim, a recent arrival in Bulgaria, had been investigated as part of a joint operation with the U.S. Federal Bureau of Investigation (FBI), for filming and distributing child pornography on the Internet.
He said police were preparing to arrest him before the murder occurred.
The Balkan state has fallen under international scrutiny in recent weeks concerning child pornography, following a report by German television indicating that Bulgarian children from the Roma community had been transported to Germany as part of a pedophile ring in 1999-2000.