When I was in law school, I did an internship with the U.S. Attorney's office in Dayton, Ohio. I became friends with an IRS Investigator, who was basically a graduate of FLETC assigned to the IRS. He had full arrest powers, and investigated tax related issues. He carried a Sig 226, if I recall. Anyways, Dayton had a fairly small federal law enforcement community. Half a dozen or so FBI agents, similar number of Marshals, maybe a few more between DEA, IRS, etc. They trained together, and would often back each other up when serving warrants, etc. It was interesting to see them work together, especially after reading about how their sueriors fight among themselves in D.C. so often.