Annapolis, MD – Anne Arundel County State’s Attorney Anne Colt Leitess announced today that a jury found Joseph Leissler, 52, guilty of all charges in the murder of John O’Sullivan, 43, another prisoner at the Maryland Correctional Institute in Jessup, Maryland. Leissler was found guilty of 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.
Leissler, one of the leaders of the Aryan Brotherhood, 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, at another prison.
“This guilty verdict is the last of three trials involving the co-defendants and I am glad that Mr. Leissler will be held responsible for his role in ordering the murder of John O’Sullivan. While the defendant did not wield a knife to kill the victim, he used his authority over fellow members to carry out this attack. The State will seek the maximum sentence for this crime, which is life without parole,” said State’s Attorney Anne Colt Leitess. “I continue to send my deepest condolences to the family and friends of John O’Sullivan for their loss.”
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 in a rival gang. In O’Sullivan’s attack, there was testimony that Leissler ordered the hit in direct retaliation and could do so as the gang’s leader.
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 is waiting to be sentenced.
Mr. Leissler will be sentenced on November 2, 2021. He faces two possible life sentences, including up to a sentence of life without parole.
The Honorable Stacy W. McCormack presided over the case.