John R. Schindler, a former professor of national security affairs at the U.S. Naval War College, where he taught courses on security, strategy, intelligence, terrorism, and military history, before joining the NWC faculty, spent nearly a decade with the super-secret National Security Agency as an intelligence analyst and counterintelligence officer.

He reports:

After 9/11, as a National Security Agency counterintelligence officer, I was involved in an Intelligence Community re-look at recent acts of terrorism, searching for possible links to foreigners. Oklahoma City was one of these. I quickly discovered, as Rohrabacher's investigators did a few years later, that the FBI and DoJ had no interest in anyone peeking into the case, which they considered closed, indeed tightly shut. Even in Top Secret channels, avenues were blocked.

In a blog post he highlights the possible role of  Andreas Strassmeir:

The most troubling angle is the role of Andreas Strassmeir, a German national who had lived at Elohim City, on-and-off, beginning in 1992. He had come to America in 1989, as an ardent fan of Civil War reenacting — as a Confederate, naturally. He became close with McVeigh, the two having met at a gun show in the spring of 1993, and the latter spoke warmly of "Andy the German," whom he phoned at Elohim City, where "Andy" was head of security, several times. Strassmeir is by any accounts an odd character.