Sao Paulo police have arrested the man they believe is "The Rainbow Maniac", a serial killer haunting the parks of Brazil's largest city and murdering gay men.

The AP reports:

"Retired state police Sgt. Jairo Francisco Franco was taken into custody Wednesday night after a witness identified him as the killer of a homosexual man on Aug. 19, said police inspector Paulo Fortunato.

Franco is suspected of acting alone in all of 13 killings between February 2007 and August 2008 at Paturis Park, a favorite meeting point for gay men, Fortunato said.

The suspect, who worked as a private security guard in a supermarket, has denied the charges, Fortunato said. He added that Franco did 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."