The breach of secrecy around Bentley's defection foiled a year-long attempt by the FBI to have her act as a double agent. Additionally, because of the shutdown of Soviet espionage activity, the FBI surveillance of the agents Bentley had named turned up no evidence that could be used to prosecute them. Some 250 FBI agents were assigned to the Bentley case, following up the leads she had provided and, through phone tap, surveillance and mail openings, investigating people she had named. The FBI, grand juries and congressional committees would eventually interview many of these alleged spies, but each of them would either invoke their Fifth Amendment right not to testify or maintain their innocence.