He is correct, except for the part about being interviewed withing days. Louis Witt was tracked down by the HSCA.
You cannot read conspiracy books and get the truth, it doesn't matter how many. Most of them take great liberty with the facts, or simply repeat the accepted myths about the evidence. If you want to know the truth you must first set aside the conspiracy books and look at the evidence.
Read Six Seconds in Dallas.
A decent book, but an old one. Written before the HSCA, which debunked a lot of the misinformation that was spread about. Its author is firmly committed to a conspiracy and isn't going to let anything change his mind. :-)
"Louis Witt was tracked down by the HSCA."
Right. Or rather the HSC made a public appeal and people who knew him identified him. And then he came forward.