More Questions For The FBI

Last December when an assistant U.S. attorney in Baltimore was found stabbed to death, the FBI made the case one of its highest priorities. Now there are troubling developments that suggest it has become a major embarrassment, reports CBS' Jim Stewart.

Sources tell CBS News that only a few weeks after the body of Assistant U.S. Attorney Jonathan Luna was found face down in a creek near his parked car in rural Lancaster, Pennsylvania, supervisors at the FBI's Baltimore field office began focusing on one of their own female agents as a possible suspect in the murder.

The rationale appears to have been that it was not Luna's work as a prosecutor which led to his death, but a personal relationship that went bad.

When an unidentified female FBI agent was found to have "referred several cases to Luna" for prosecution she was "questioned about her private life," "ordered to turn over her private computer for a search" and was "asked if she had been having an affair" with Luna. The agent "denied the implication" and "protested the questioning."

FBI headquarters now admits that interrogation was "wrong," and may have been prompted by "personal" animosities on the part of supervisory agents. The "potentially inappropriate behavior" is now under internal investigation, according to a bureau spokesman.

The Luna homicide had been under the direction of former acting Special Agent in Charge Jennifer Love.

"The FBI is aggressively investigating the circumstances surrounding Jonathan's death," she said back in December.

Now, a senior agent working for Love - and possibly Love herself - appear to be the subject of the internal FBI probe.

Lost in all this was the search for Luna's real killer. Sources tell CBS that while their supervisors were on the witch hunt, field agents continued their work and have recovered a knife that may have been the actual murder weapon - a discovery that has led to what one source calls "a very promising suspect."