This is some interesting info about Mac Wallace:

"Malcolm Wallace, convicted in a 1951 murder and suspected in others, has been linked to the 1961 death of U.S. Department of Agriculture investigator Henry Marshall. Marshall was reportedly close to connecting Lyndon Johnson to fraudulent activities involving businessman and convicted swindler Billy Sol Estes.

Estes alleged in 1984 that LBJ ordered the killings of Marshall, President Kennedy, and half a dozen others, and that Wallace carried them out. A grand jury decided that same year that Henry Marshall was murdered as a result of a conspiracy involving then-Vice President Johnson, his aide Clifton Carter, and Wallace. No charges were possible since all three men were by then deceased.

Wallace was killed in a single car automobile accident in January 1971.

Barr McClellan, a Houston attorney and part of the Texas research team, told Fair Play that he began to focus on Wallace during his work as attorney-partner with Ed Clark, whom he described as an Austin power broker and one of those behind the assassination. "John Cofer, Wallace's attorney from the start, was our partner specializing in criminal cases," McClellan said. "From that position of insight, I knew Wallace played a key role in the assassination.""

This is from:

[link to spot.acorn.net]

When I was a kid I remember hearing that Billy Sol Estes was a major scandal for LBJ. I think JFK might have been considering dropping LBJ for the 64 race because of it, if I remember right.