Authorities charged eight policemen with murder Tuesday for death-squad killings that left 30 people dead on the city's outskirts last week.

Four of the officers already had been charged by federal police, but state police were seeking new charges because of uncertainty over federal jurisdiction.

The chief suspect was Carlos Jorge Carvalho, the first suspect to be identified by witnesses who said they saw him shooting at the crime scene. They said Carvalho later returned to the crime scene and talked with uniformed police who arrived after the shootings to investigate.

In total, police were holding 12 officers in connection with last Thursday's shooting. Police believe four officers did the shootings and eight provided backup.

Authorities believe the killings were a show of force by rogue police angered by the arrest of eight other officers caught on film while disposing of two bodies.

The bloodiest massacre in years in a state known for its violence, the shootings left many perplexed. Only two victims had criminal records and five were teenagers, shot while playing video games at a bar.

Rights groups have likened the massacre to attacks by death squads — shadowy associations often made up of off-duty or retired officers who are hired by businessmen to kill undesirables.

Brazilian death squads created an international uproar 12 years ago, when they were blamed for the killing of eight children sleeping outside a church in downtown Rio. A month later, police killed 21 residents of the Vigario Geral (search) slum, apparently in revenge for the killing of several police.

The homicide rate across Rio de Janeiro state (search) is among the highest in the world at around 50 per 100,000 residents.