By Andrew Cawthorne
CARACAS (Reuters) - Fifteen corpses, three of them headless, have been found in a mass grave at a Venezuelan prison and more may be discovered, investigators said on Saturday.
The grisly find this month at the General Penitentiary in central Guarico state has thrown a spotlight on the South American nation's crowded, violent and gang-dominated prisons where scores of inmates die each year.
The public prosecutor's office said 20 forensic experts combing the site at a prison stable had found the remains of at least 15 people, though three were missing skulls.
"We presume there are more corpses," it said in a statement.
Authorities have given no explanation for the deaths and there has been little national outcry given the litany of horror in Venezuela's prisons in recent decades.
Rights group A Window On Liberty has said the number of victims, presumed killed in gang violence before the prison was recently closed for refurbishment, could rise to 100.
"Whether 14, 50 or 100, they were people under the state's responsibility," the group's coordinator Carlos Nieto said, adding that the facility used to house 9,000 inmates.
Venezuela's prisons are notorious for ease of access to weapons and drugs as well as mobile phones and computers hooked up to the Internet, allowing inmates easy access to the outside world, often to run criminal activities.
Some prisons have discos and even swimming pools.
The country's more than 30 facilities house about 50,000 people, but were built for a third of that, rights groups say.
In perhaps Venezuela's worst single prison incident, about 130 prisoners were burned or hacked to death with machetes during gang fights at Sabaneta jail in Maracaibo in 1994.
Late last year, gruesome accusations surfaced that two men were murdered, mutilated by a confessed cannibal then fed to fellow prisoners during rioting at a police detention center in western Tachira state.
(Editing by James Dalgleish)