A New Mexico father is accused of fatally shooting his adult son with a shotgun before attacking the victim’s girlfriend as she knelt beside his body, according to police and court documents.
Mark Leib, 64, was arrested after the deadly confrontation Sunday night, Sept. 20, at a home on Sabre Court NW in Albuquerque.
His son, 34-year-old Matthew Leib, died at the scene.
Police say what began as an evening of drinking, watching football and spending time together escalated into a terrifying family confrontation after Mark returned home and allegedly began making threats.
According to a criminal complaint cited by Law&Crime and local Albuquerque outlet ABQ RAW, Matthew was inside the home with his girlfriend and a friend when his father allegedly began saying he was going to kill someone and hurt everyone around him.
The friend told investigators he became alarmed enough to warn Matthew that they needed to leave.
Matthew’s girlfriend reportedly tried to calm Mark down and initially got him into a bedroom.
But investigators say he later emerged carrying a short-barreled shotgun.
The girlfriend told police that Mark pointed the weapon toward her face and threatened to kill her.
At one point, Matthew allegedly stepped between his father and girlfriend and confronted him.
The situation continued deteriorating.
According to the complaint, the girlfriend and friend eventually left the home but quickly realized Matthew had remained behind.
When they returned looking for him, Mark allegedly came outside and announced that he had shot his son.
The girlfriend rushed into the house and discovered Matthew lying wounded in a hallway.
She grabbed onto him and called 911.
Police allege Mark then came back inside and struck her repeatedly in the back of the head with the stock of the shotgun while she was crying and holding Matthew.
Officers arrived shortly afterward and detained Mark.
Emergency personnel attempted to help Matthew, but he could not be saved.
A neighbor had also called authorities after hearing a loud argument followed by sounds she believed were gunshots.
Investigators say Mark separately contacted 911 and repeatedly admitted that he had killed his son.
When officers took him into custody, police say he continued making statements about the shooting.
Detectives later advised him of his Miranda rights and attempted to interview him at the police station.
Mark declined to answer questions and invoked his Fifth Amendment right to remain silent, according to the complaint.
Police searching the home reportedly recovered the shotgun, two spent shell casings and evidence of bullet impacts in the hallway.
Matthew’s body was also found there.
Mark was arrested on an open count of murder, two counts of aggravated assault with a deadly weapon and one count of aggravated battery with a deadly weapon.
An “open count” of murder under New Mexico procedure allows prosecutors to pursue the degree of murder supported by the evidence as the case moves forward rather than locking the prosecution into a specific degree at the initial charging stage.
The allegations have not yet been proven in court, and Mark Leib is presumed innocent unless convicted.
The Albuquerque Police Department lists the Sept. 20 Sabre Court killing among its solved 2026 homicide cases. As of Sept. 21, APD had recorded 45 homicide victims in the city for the year, down from 54 at the same point in 2025.
The investigation remains active as prosecutors prepare the case against Leib.
