Brazilian police have launched an investigation into the killing of an official at one of the country's most notorious prisons.
Brazilian prisons have seen many riots in recent years
Henrique Fernandes da Silva, who was security chief at the Bangu 3 penitentiary complex in Rio de Janeiro, was shot at his home on Saturday.
He is the fifth official from this jail to have been murdered in five years.
Bangu 3 holds 900 prisoners - among them some of Rio's most dangerous drug-traffickers.
Police said that Mr Fernandes da Silva, 35, was shot nine times in front of his wife and children at his home in a western part of the city.
The attackers reportedly used a pistol and a rifle.
Fellow prison officials said Mr Fernandes da Silva had received threats after he launched an operation to seize drugs, mobile phones and radios at Bangu 3.
Violence is common in Brazil's jails, which hold more than 190,000 inmates.
Rioting has been blamed on poor living conditions, but also on organised crime gangs that enjoy power and influence in the penitentiary system.
In recent years, the Bangu 3 prison has seen several uprisings led by the Red Command, said to be the biggest gang in Rio de Janeiro.