A jury found James Crumbley guilty on four counts of involuntary manslaughter Thursday.
Crumbley's son shot and killed four people and wounded seven others at Oxford High School in Michigan in November of 2021.
Prosecutors accused James Crumbley of failing to secure a firearm and neglecting to address his son's mental duress.
Prosecutors said Crumbley had a "legal duty" to keep his son Ethan from harming people.
Crumbley's attorney said he couldn't have predicted that his son would commit a shooting,
The verdict matches that handed down to James Crumbley's wife Jennifer, who was convicted of involuntary manslaughter in the shooting in February.
The parents are the first in the U.S. to be criminally charged in connection with a child's mass shooting.
Their son had drawn pictures of firearms and injured people on his schoolwork and looked up pictures of ammunition while in class. He had written messages acknowledging his need for and asking for help with his mental health.
The day of the shooting, his parents met with him and staff at the school, but declined to take him home. Prosecutors say James Crumbley called 911 to report a missing handgun after the shooting occurred.
Prosecutors say Crumbley neglected the "easiest, most glaring opportunities" to avert the shooting by not taking his son home and by not securing the gun with a lock he owned.
Crumbley's son is serving a life sentence in prison for terrorism and murder.
Mother of Michigan school shooter found guilty of manslaughter
The jury of six men and six women reached its decision on its second day of deliberations.
