He was a suspect in the assassination attempt on Sheriff Buford Pusser and in the death of Buford's wife on August 12, 1967. Nix has repeatedly refused to comment about Pusser's claims that he was one of his wife's killers.
Nix was later involved in the 1987 murder-for-hire killing of Judge Vincent Sherry and his wife Margaret, in Biloxi, Mississippi. His co-conspirator, Biloxi Mayor Pete Halat, had stolen hundreds of thousands of dollars from Nix and blamed it on his law partner, Vincent Sherry. Nix ordered a hit from prison and was later sentenced to isolation for the rest of his life.
According to an October 20, 1999 appeal from the United States District Court For the Southern District of Mississippi, "while serving a life sentence for murder at Angola State Penitentiary, Nix built a criminal empire from which he hoped to earn enough money to buy his way out of prison. Although he dabbled in insurance fraud and drug dealing, Nix’s primary money-making scheme was a 'lonely hearts' scam designed to defraud gay men. Nix and his prison syndicate would place personal advertisements in national gay-themed magazines. When men would respond to these ads, Nix or one of his associates would indicate that he was having financial difficulties and needed the respondent to wire money to a Nix associate outside prison. Nix acquired hundreds of thousands of dollars from this scam".
Nix, Federal Bureau of Prisons (BOP) #20921-077, is currently incarcerated at the United States Penitentiary, Terre Haute. Nix's co-conspirator, Halat, BOP # 20918-077, was located at the CCM Montgomery, Alabama until his release on April 24, 2013. Previously, Halat was located at the Federal Correctional Complex, Oakdale, and the Federal Correctional Institution, Butner Low.
- The Sun Herald, The Dixie Mafia:Sheriff Leroy Hobbs, Drugs and Murder, Gene Swearingen and Anita Lee, September 15, 1990
- Dixie Mafia: Prison Gang Profile Archived 2006-07-18 at the Wayback Machine.
- Cases No. 97-60263 and 97-60704, "Appeals from the United States District Court For the Southern District of Mississippi," UNITED STATES COURT OF APPEALS For the Fifth Circuit, October 20, 1999.
- Kirksey McCord Nix ([https://www.webcitation.org/6FL7HAUP3?url=http://www.bop.gov/iloc2/InmateFinderServlet? UPDATE: Nix is currently at FCI-El Reno, Oklahoma and is scheduled for release on April 3, 2022. KIRKSEY MCCORD NIX Register Number: 20921-077 Age: 74 Race: White Sex: Male Located at: El Reno FCI Release Date: 04/03/2022 Transaction=NameSearch&needingMoreList=false&FirstName=kirksey&Middle=&LastName=nix&Race=U&Sex=U&Age=&x=0&y=0 Archive]) Federal Bureau of Prisons. Retrieved on July 24, 2010.
- "Peter Halat Jr. Archived 2012-06-14 at the Wayback Machine." (Archive) Federal Bureau of Prisons. Retrieved on March 23, 2013.
- "Peter Halat Jr." Federal Bureau of Prisons. Retrieved on February 2, 2011.
- "Peter Halat Jr. Archived 2012-06-14 at the Wayback Machine." Federal Bureau of Prisons. Retrieved on July 24, 2010. "Archived copy". Archived from the original on June 29, 2011. Retrieved 2012-06-14.