Joseph Kennedy, 67, was arrested in Florida and named as a person of interest for the murders of Mark, 32, and Billy Chastain, 30, and Mike Sparks, 32.
Teresa Stevens told DailyMail.com her son Alex, 29, and his friends Mark, 32, and Billy Chastain, 30, and Mike Sparks, 32, were ;first shot multiple times, before being chopped up.
Okmulgee police called the case of four men who disappeared before they were found murdered "very rare." Police arrested a person of interest on Tuesday.
Investigators now believe the four men planned to "commit some type of criminal act," citing a witness who told investigators they had been invited to join and to "hit a lick big enough for all of them."