Re: Colorado Aviation, and Herman Butler, it looks like you've done part of the homework already. Michael Fitzgerald was named in the wrongful-death lawsuit Pamela Murphy initiated with regard to her husband's demise. So was American Western Plastics. Here's a legal appeal filed by Michael Fitzgerald and Dalton Carl Smith with regard to some financial chicanery they got convicted of, relating to American Western Plastics: http://vlex.com/vid/america-dalton-carl ... s-37634081
Dalton Carl Smith, or D'Alton Smith, had mob ties, being the son-in-law of New Orleans mob boss Carlos Marcello and having been involved in various attempts to get Edward Grady Partin to recant his testimony against Jimmy Hoffa. You will find Smith's name mentioned in connection with Murphy's attempts in that direction, for instance.
Re: the FBI files, I just want to reiterate that FOIA requests are reputedly very slow in being fulfilled, so it could be a year or more before we see any results on that front.