Jeff Beard was abducted and brutally murdered by Stanley Robinson, a Chicago police officer. An F.B.I. informant, William O'Neal accompanied Robinson on the night of the murder. Robinson was convicted of the crime in 1973. P brought this suit against D, an F.B.I. agent who participated in the investigation of Robinson's activities. P alleges that D's reckless conduct of the Robinson investigation resulted in the deprivation of Jeff Beard's constitutional rights, giving rise to a Bivens action for damages. P introduced testimony to establish that D and O'Neal had a long-standing relationship. P established that in his role as informant O'Neal participated in criminal activities with other Black Panther Party (BPP) members and that D had knowledge of these activities. D also introduced evidence establishing that O'Neal was successful in preventing crimes on a number of occasions. O'Neal ceased activity as a BPP informant in early 1972. O'Neal and Robinson set out to perform a murder contract. Robinson only knew that the intended victim was a tall black man named Jeff with a high natural hairstyle. They eventually spotted their mark and Robinson killed Jeff Beard. P sued D. The trial judge permitted Kocoras, the Assistant U. S. Attorney assigned to the Robinson case, to testify at trial that D had a reputation for truthfulness. P contends that this was an impermissible use of reputation evidence under Rule 608(a).