Two brothers were arrested in the Amazonian city of Manaus in connection with the murders of four gay men, Brazilian authorities said Thursday.

The investigation was initiated in November after the death of journalism student Steve Host da Costa Barros, 36.

The older of the two brothers, considered by authorities to be "a maniac," met Barros in a bar and 20 days later robbed and murdered him with the help of his sibling, sources with the Amazonas state police told Efe.

After the arrests, police found objects belonging to the victim that were kept by the brothers, a fact that - along with the coldbloodedness of the crime, strengthened authorities' suspicions that the pair could be involved in serial killings.

The brothers confessed during questioning to murdering Barros and police found evidence showing that they were involved in the murders of three other gay men in Manaus during the past several months of 2013.

The older brother is suspected of having acted alone in the murders of six other men, the sources said. EFE