Lawyers for James “Whitey” Bulger have identified the late federal prosecutor Jeremiah O’Sullivan as the federal agent who allegedly gave the notorious gangster immunity to commit his reign of terror.

Attorney J.W. Carney Jr. of Boston made the bombshell allegation in a court filing late Wednesday in which he again called for a US District Court judge to recuse himself from presiding over the case. He said the judge has an apparent conflict of interest as a former prosecutor who worked at the same time as O’Sullivan, a former US attorney who died in 2009 at age 66.