The original 1958 investigation quickly focused on several groups of individuals. According to the investigators' case notes, the list of suspects was eventually narrowed to the following:
Investigators believe the strongest motive exists for this group involved with payoffs and grudge against Richard Izard. Investigators have been unable to determine the nature and total amount of payoff to Richard Izard by Perch. However, the amount was thought to be in excess of $5,000 for insider information and a guarantee of layoff protection.
This group comprised the leaders of the union movement at Bowlan (in alphabetical order):
Frank Abbott, Robert Abbott, Charlie Duncan, Fred Earle, Wes Hannaford, Steve Ibello, Glenn Johnson, Joe Mitchell, Lou Nash, Elliot Perch, Ralph Quillens, Elbert Warren
Suspects not cleared from this group: Elliot Perch, Ralph Quillens, Elbert Warren
The following group of union sympathizers have a reputation for impulsive violence, a history of arrests for public disturbance, fighting, vandalism, heavy drinking and are thought to have been the muscle used to back up organizing efforts at Bowlan.
Louis Corbett, Howard Hadley, Walter Hinkley, Glenn Johnson, Ed Rebstock, Jimmy Warren (considered the instigator and leader of this group)
Suspects not cleared from this group: Walter Hinkley
- Jimmy Warren and Howard Hadley were only partially cleared. Investigators' notes indicate that they found their alibis slightly suspect due to the reputations of those providing the alibis. Both men were considered to be heavily drinking hotheads with a reputation for violent altercations. They were considered by investigators to be potentially involved in a conspiracy or to have guilty knowledge of the crimes.
- Jimmy Warren was known to have been making threats and throwing punches at Sid's on the afternoon of the murders. This information can be placed in the context of a hunch based on experiences with the men rather than on any hard evidence.
- Elbert Warren remained the chief suspect throughout the investigation.
The men in this group are toughs prone to heavy drinking and violence. All have prior arrests for assault and public disturbance, drunk and disorderly conduct individually and as a group.
Danahy (considered the leader and instigator of this group) has a long history of romantic attachment to Lisa Izard and harassment of the Izard family
Danahy may have taken the opportunity of the layoffs at Bowlan to conspire with one or more of this group in the murder of Richard Izard. It is believed that Lisa Izard was not a target of this attack.
All of the following are Bowlan employees, all are between the ages of 25 and 29 years (1958), and all have been friends since childhood.
Harvey Booker, Pete Corey, Jessie Danahy, Jack Peach, Jeff Skinner, Frank Valenti
Suspects not cleared from this group: Harvey Booker, Pete Corey, Jessie Danahy
Elroy Murphy — the last person known to see missing child Ricky Izard. Murphy was considered and cleared.
Thomas Joe Hinkley — considered as a potential conspirator with his brother, Walter Hinkley. Some suspicion was attached to his finding the bodies and his manner in interviews. Thomas Joe Hinkley has been cleared.
The following Bowlan employees are considered low on the suspect list. However, they have no verifiable alibi for the time of the murders, they showed some indication for suspicion in their interviews or actions, and they cannot be removed from consideration:
Nathan Buck, Earl Long