Annapolis, Md. – Anne Arundel County State’s Attorney Anne Colt Leitess announced today that Joseph Leissler, 52, was sentenced to life without the possibility of parole in the murder of John O’Sullivan, 43, another prisoner at the Maryland Correctional Institution in Jessup. Additionally, he was sentenced to another life sentence and 40 years to run concurrently.

A jury found Leissler guilty of all charges which included first-degree murder, supervising a criminal gang, participation in a criminal gang resulting in death, participation in a criminal gang, and conspiracy to commit first-degree murder on August 23, 2021.

Leissler, the leader of the Aryan Brotherhood in Maryland, directed underlings Vincent Bunner, Calvin Lockner, and Brian Hare to viciously attack O’Sullivan with homemade prison knives. O’Sullivan was a ranking member of a rival gang, Dead Man Incorporated (DMI). The murder was apparently in retribution for a gang-related assault, not involving any of the parties, which occurred at another prison.

“The defendant has been leading a violent life inside the jail and this sentence sends a clear message that justice doesn’t stop at the prison door and that any violent acts committed within the prison will have real-world consequences,” said State’s Attorney Anne Colt Leitess. “It’s my hope that the verdict provides the loved ones of Mr. O’Sullivan with a sense of solace, now that the fourth person involved in his death was held accountable and sentenced.”

In a victim impact statement read in court, Mr. O’Sullivan’s mother wrote that life has been turned upside down since his death. She wrote, “John was my only child. When they took his life, they took mine as well. I have been in this black hole since that day.”

“While the defendant did not wield a knife to kill the victim, he used his authority over fellow gang members to order them to carry out this attack on his behalf and to further the gang’s reputation. The State sought the maximum sentence for this crime, which is life without parole,” said State’s Attorney Anne Colt Leitess. “I am grateful for the efforts of the Maryland State Police Homicide Unit that investigated this crime, as well as the members of the Intelligence and Investigative Division of the Department of Public Safety and Correctional Services which assisted in the gang-related investigation and recovery of evidence in this case.”

State’s Attorney Anne Colt Leitess prosecuted the case on behalf of the citizens of Anne Arundel County.

On August 14, 2016, at the Jessup Correctional Institute, inmates located in Building F were returning to their cells after their recreation break. Shortly after, an inmate, identified as John O’Sullivan, entered his cell to retrieve his belongings to take a shower when he was attacked by three inmates, identified as Vincent Bunner, Calvin Lockner, and Brian Hare. The trio stabbed O’Sullivan with homemade metal knives. Video surveillance captured the three defendants attacking O’Sullivan as he attempted to flee his cell and run for help toward the control booth area of the tier. Correctional officers entered the tier in response, and using pepper spray, disarmed the suspects and ordered them onto the ground. O’Sullivan succumbed to his injuries and died at the scene. The Office of the Chief Medical Examiner ruled that O’Sullivan died from blood loss due to 54 stabbing and cutting wounds.

During the weeklong trial, former members of the Aryan Brotherhood stated that Leissler directed attacks on at least six other individuals on behalf of the gang. Their testimony included the rule that only a high-ranking gang member could order an attack on O’Sullivan because of his status as an elder in a rival gang. In O’Sullivan’s attack, there was testimony that Leissler, as the gang’s leader, ordered the hit in direct retaliation for an assault committed on another member of the Aryan Brotherhood at another prison. Evidence presented at trial showed O’Sullivan had wanted to keep the peace between the groups and avoid any confrontation. O’Sullivan was set to get out of prison just months after the attack.

In 2020, two of the accomplices, Bunner and Lockner, were tried and convicted of second-degree murder and were each sentenced to the maximum time of 30 years consecutive to sentences they were already serving. Bunner is currently serving a life sentence and Lockner, a 30-year sentence. Brian Hare pleaded guilty to first-degree murder in the attack and testified against his co-defendants at trial. He was sentenced to life in prison with all but twenty years suspended.

The Honorable Stacy W. McCormack presided over the case.


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