Opinion ID: 201912
Heading Depth: 2
Heading Rank: 3

Heading: immunity promise

Text: 20 Finally, McInnis challenges his revocation sentence on the strength of his claim that a deputy marshal promised him that, for disclosing the location of the marijuana, he would not be prosecuted. The district court was entitled to disbelieve testimony given by McInnis's girlfriend and other friends of McInnis which was squarely contradicted by the deputy's testimony. See United States v. Whalen, 82 F.3d 528, 532 (1st Cir.1996) (stressing the difficulty of upsetting on appeal credibility determinations by a fact-finder). But even if the deputy had made such a promise, it would lack legal significance for lack of authority to offer such immunity. See United States v. Flemmi, 225 F.3d 78, 86-87 (1st Cir.2000) (requiring a specific source of authority for granting immunity). The Marshal Service is an investigatory arm of the Department of Justice, not a prosecutorial agency. It lacks authority deriving from its investigatory role, even when operating in conjunction with probation officers, to make promises to suspects binding on the United States Attorney. As this court explained in Flemmi, the power to investigate does not necessarily encompass (or even reasonably imply) the power to grant use immunity. 225 F.3d at 87. McInnis has failed to identify a source of authority for the deputy to make a promise of immunity.