It wasn't until August 1984 that the FBI finally began to investigate Mitrione. And the bureau would ultimately come to the same conclusion about the bombing as Regan -- that Mitrione likely planted the device. Only it kept that a secret.
Donna remembers begging the FBI on a weekly basis to investigate her case. She was ignored until more than a year after Gary's disappearance. One day, she believes it was in early 1985, an FBI agent called and said he wanted to talk about her husband. She was ecstatic.
When two agents arrived at her apartment, Donna was met with grim faces. The lead agent, a tall black man, sat down at the kitchen table and started asking questions. A quiet white agent sat nearby. As she talked about Gary, the black agent accused her of holding back information. "You better tell us everything you found out or we're going to throw you in front of a grand jury so fast it'll make your head spin," she recalls him bellowing.
As the interview progressed, Donna's anger grew.
"What about Gary?" she asked the agents. "Do you want to find Gary?"
"I'm the one asking questions here!" the lead agent yelled at her.
"Oh, you're not going to tell me anything about my husband?" Donna asked. She could feel her voice rising. "You're not going to answer me? You should be looking for Gary!"
She stood up and pointed to the door.
"Get out of my house!" she demanded. "Get out now!"
At this bit of ferocity, the two FBI agents left.
Donna's face reddens with anger as she recalls that meeting, mostly because of what she's learned since. The FBI, at that very time, was investigating Operation Airlift. One of the lead agents in the case was James Brown, an African-American who usually worked with a white agent named Frank Buttino. Donna believes it was Brown and Buttino who visited her apartment that day, but, like so many things related to Airlift and her husband's disappearance, she can't be sure.
The best insider account of the FBI's special investigation of Mitrione's crimes comes from former agent Buttino, who was based in San Diego. In his 1993 book, A Special Agent: Gay and Inside the FBI, Buttino characterizes the Mitrione investigation as "one of the most important in FBI history." In the book, which details Buttino's ouster from the bureau after it was revealed he was gay, the former agent showers praise on the case's supervisory agent, John Morris, who came from Boston. Buttino recounts Morris' telling the team of eight agents: "Let's hope we don't have a scandal on our hands. But if we do, let's conduct the investigation thoroughly and not make the bureau look any worse."
Several months into the investigation, Mitrione finally confessed to participating in the drug-smuggling operation and was arrested on drug and bribery charges. Buttino described the rogue agent as twitching nervously in his chair as he confessed in a Miami hotel room. Later, the team of agents had a "final dinner," Buttino wrote. "I stood and looked over at John Morris. Raising my glass, I said, 'To one of the best supervisors I've ever worked for,'" Buttino recounted.
"We can be proud," Morris told the agents.
The celebration, however, proved to be premature; they'd overlooked the attempted bombing and the Esposito murder. Shortly after the dinner, the agents learned from then-U.S. Attorney Stanley Marcus that Mitrione had failed a portion of a lie detector test where he denied setting the bomb on Sandini's car. The news was devastating, Buttino wrote, and made him wonder: "Had we been taken in by Mitrione?"
Only then did the FBI investigate the attempted bombing. An internal memo from the time reveals the self-protective mindset of the agency as it came to realize the extent of the former agent's crimes: "This investigation, which is being conducted by a special FBIHQ [headquarters] investigative team, has been severely hampered by recent developments indicating a strong likelihood that Mitrione is culpable in the attempted murder of Sandini."
The FBI and U.S. Attorney's Office hid those suspicions from the public and never prosecuted Mitrione for the attempted bombing. On March 14, 1985, he pleaded guilty to narcotics and bribery charges and was sentenced to six years in prison (though he would serve only three). The plea bargain made national news. On the front page of the New York Times, then-FBI Director William Webster described the agent's downfall this way: "The corrupting power of drug money is one of the obvious reasons why this number one crime problem must be conquered in our country... This sad case illustrates our relentless determination to police our own ranks."