A retired state police sergeant has been arrested in Brazil in connection with the murders of 13 gay men in Sao Paulo.

Jairo Francisco Franco was taken in for questioning on Wednesday night and is thought to have acted alone.

All the men bar one were shot to death, the other was beaten, in a park known as a cruising ground.

He denies the charges.

A witness said the former police officer, who works as a private security guard, was a regular visitor to the park.

“We have a credible witness who says he saw Franco pump 12 bullets into a black gay man inside the park,” police inspector Paulo Fortunato told AP.

“We are convinced he is the rainbow maniac we have been looking for.”

Police have dubbed the serial killer the Rainbow Maniac, a reference to the multi-coloured Pride flag, an international symbol of the gay community.

The first body was found in July 2007 and the most recent in August this year.

All the victims were aged between 20 and 50.

One died from blows to the head – the other 12 had been shot.

In May the world’s largest gay pride parade took place in Sao Paulo when five million people attended.