A retired Montreal police officer tried to sell a list of informants to the Mafia, according to information obtained by Radio-Canada.
After his retirement in January, the officer allegedly tried to sell the list for a six-figure sum.
Police said he was one of only two or three people who had access to the list.
Didier Deramond, of the Montreal police, said information was received in April 2011 through a wiretap investigation. That information led to the suspect's arrest in October, he said.
A search warrant was issued after his arrest, and the list of informants was seized.
Police said the identities have not been compromised.
No charges have been laid.
Deramond said the officer worked for Montreal police for more than 30 years.
A second person was arrested in connection with the case. Police said the investigation is ongoing.