When two FBI came looking for me, they went to my mother's old employer that she had left 6 years prior. Someone at the school called her and she called me.

I called the agents and they asked if I could meet them at their office. I agreed.

I had invested in a project with an out of state person. He was referred to me by a close friend. When I stopped sending money, the person disappeared. This person had a reputable background, a family and lived in an expensive house. But he'd call me crying begging for money, claiming other investors were closing soon.

I being young and foolish, contacted his partners and my friend. I could had handled it better but I knew I hadn't broken any laws. I did tell him I'd tell everyone he knew that he was a con-artist.

The FBI agents were comically dense. One was dressed in tactical gear. They claimed they had an email I sent where I threatened the investor's young children. I strongly denied this and then asked to see it.

They refused to show me and responded, "We are the Federal Bureau of Investigation not the Federal Bureau of Information". Then they asked me if I was a member of a foreign intelligence service but mispronounced the name.

They told me not to contact the person and I should consider a lawsuit.

Before I met with them, I did ask a US based intel person what he thought. He said FBI agents are sometimes employed by private interests and that I should ask for identification and verify it with the local branch. I'm not sure if this is actually true but it certainly wasn't in my case.