6:14PM GMT 31 Oct 2011
Marcelo Freixo said on Monday he will leave this week for an unidentified European country with the help of human rights group Amnesty International.
"I plan to stay outside Brazil for a while. I want this time to adjust my security precautions and to call the attention of the authorities," he told Reuters by telephone.
"I'm treating this as my own personal problem but clearly it is a public security problem too."
Mr Freixo led an investigative commission in 2008 that looked at militias – illegal groups made up of off-duty and former police officers and firefighters that have expanded their presence in Rio's poorer communities in recent years.
Organised crime within the security forces is among the most serious problems Rio faces as it prepares to host global showpiece sports events – the World Cup in 2014 and the Olympics two years later.
The militias were originally applauded by some politicians as a solution to the drug gangs that dominate many slums but reportedly engage in criminal activities themselves, including extortion and summary executions.
Mr Freixo's investigation led to the indictment of 225 people, including politicians, police officers and firefighters.
"The threats have always existed but now they have intensified," said Mr Freixo, who travels in a bullet-proof car, has a 24-hour bodyguard and is widely believed to be the model for the crusading politician in the hit 2010 Brazilian movie "Elite Squad 2."
In August, gunmen killed a judge who took a hard line against militia members, ambushing her as she arrived home in Niteroi, across the bay from Rio. Eleven police officers have been arrested on suspicion of involvement.
Orignal From: Brazilian MP forced into exile over Mafia threats