A Boston news writer postulates that Rossetti may have been working for the FBI for "something like 20 years" Apparantly it was that far back that the DEA had their eyes on Rossetti, but FBI Agent Mike Buckley (identified by the writer as Rossetti's handler) had them back off.
http://www.boston.com/news/local/massach...r_fbi_bungling/

Buckley was also on the team of agents who were later disgraced over their handling of the Bulger/Flemmi affair. In Flemmi's testimony, he identified Buckley as one of the agents that regularly accecpted gifts from he and Bulger, which Buckley denied.