(Sao Paulo, Brazil) Brazilian police say a retired officer has been detained in connection with the murders of 13 gay men in a low-income suburb of Sao Paulo.

Police inspector Paulo Fortunato says Franco is suspected of acting alone in all of the 13 killings.

The murders took place between February 2007 and August 2008 at Paturis Park, a favorite meeting point for gay men.

Fortunato says the suspect, who worked as a private security guard in a supermarket, denies the charges.

He says Franco does not yet have a lawyer.

"We have a credible witness who says he saw Franco pump 12 bullets into a black gay man inside the park,” Fortunato said in a telephone interview.

A second witness said Franco visited the park frequently, "apparently cruising for gay men and victims,” Fortunato said.

Police have dubbed the killer of the 13 men as the "rainbow maniac,” a reference to the gay-pride symbol.

"We are convinced he is the rainbow maniac we have been looking for,” Fortunato said.