The informant would turn out to be Perry Russo. You can read more about Clyde Limbaugh here. Jim Garrison was in Las Vegas where he was meeting with Lawrence Schiller and James Dondson, the man who was with Clay Shaw the weekend of the assassination in San Francisco. Here's another reason why Garrison asked for a preliminary hearing.
The reference to Omaha was in regards to Sandra McMaines who was, at one point, Perry Russo's girlfriend. She had married and was living in Omaha. Russo had told Garrison that she was at the party with Ferrie and Shaw. She would later tell Shaw's defense team that she was not there and did not meet David Ferrie until 1965.
Shaw's entry for March 9, 1967 notes an important point about his arrest - he could only travel outside New Orleans Parish with the permission of Garrison's office.
"I was delighted at the chance for an excursion and we went across the river bridge looking at the city sparkling in yet another beautiful day. On the other side of the river I needed cigarettes and a rest room and so we turned off the highway. I suddenly found myself in Jefferson Parish which is technically a violation of my bond so we hastened back into Orleans and on to the commissary."
A good example of what Shaw had to do to leave New Orleans. This was in a newspaper from January 3, 1968.
Shaw and his lawyers discuss the possibility of hiring a famous lawyer like F. Lee Bailey:
"The difficulty, of course, is that all these people are famed for getting people out of things that they have done; and I have done nothing and, therefore, am a little reluctant to use their services. Moreover, there is bound to be some bias, even if it is subconscious, on the part of the Judge and jury against a "Yankee lawyer' who comes to defend a client."
That was indeed part of the problem that Jack Ruby faced after hiring Melvin Belli as his attorney.
Shaw notes that the Louisiana Weekly criticized the "Roman circus atmosphere which has developed":
"Under these circumstances, it appears that Mr. Garrison should be making every effort to make his case as valid as possible so that the accused conspirators might be brought to justice, rather than giving his role as a publicist first priority."
Shaw read that Garrison's office had given Dean Andrews the choice of taking a lie detector test or sodium pentothal. This was true, and here is the letter that was sent to Monk Zelden, Dean Andrews' attorney, offering "memory refreshing procedures":
Here is the article from the New Orleans Times-Picayune from March 7, 1967 about the ACLU:
This article from the New Orleans Times-Picayune of March 8, 1967 discusses the various motions, the ACLU and the issues of private money paying for a public investigation.