Gilani Shepiyev, 36, was shot dead near the entrance to his home in Moscow at around 1:00 a.m. (22:00 GMT). The killer shot Shepiyev twice with a gun fitted with a silencer before making his escape along with an accomplice in a car.
"The killing is a contract murder and is directly linked to the victim's former activities," the source said. A criminal case has been opened and an investigation is underway.
The killed Chechen top official was responsible for supervising law enforcement agencies in the troubled North Caucasus republic between 2004 and 2006. He moved to Moscow after he was seriously injured in an attack in central Grozny in 2006.