(CBS DETROIT) - A jury has found James Crumbley, the father of the Oxford High School shooter, guilty of all four counts of involuntary manslaughter.

The jury returned a unanimous verdict on Thursday after a nearly week-long trial to determine if the father holds any responsibility for the Oxford High School shooting, where his son killed four students, Justin Shilling, Madisyn Baldwin, Tate Myre, and Hana St. Juliana, and injured seven other people on Nov. 30, 2021.

Jurors deliberations began on Wednesday.

Attorney Ven Johnson, who is representing the victims' families, issued the following statement:

"Today, a 12-person jury unanimously found James Crumbley, the father of the Oxford High School shooter, guilty as charged for his gross negligence, which ultimately played a causal role in the deaths of four OHS students. This guilty verdict, along with those found against the shooter's mother, Jennifer Crumbley, won't bring back the lives of these four students, but it represents one more step towards holding everyone responsible accountable under the law, which is justice for the victims' families and the Oxford community.

"We are eager for the decisions of both the Michigan Court of Appeals and the U.S. 6th Circuit Court of Appeals in our civil lawsuits. We are resolute in our determination to hold Oxford Community Schools and various OCS employees accountable, as they could have prevented the shooting, as indicated in their own district's Guidepost Solutions investigative report. Until everyone responsible for this tragedy is fully and legally held accountable for their role, our clients and our firm remain steadfast in our fight for justice."

Crumbley is accused of not keeping the gun used in the shooting safely stored away and not getting his son the necessary help for his mental health needs.  

Defense attorney Mariell Lehman argued that James Crumbley was not aware that his son had access to the gun.

The conviction comes after a jury found his wife, Jennifer Crumbley, guilty of the same charges in February.

James and Jennifer Crumbley will each be sentenced on April 9.

Closing arguments in James Crumbley trial

Closing arguments began on March 13, after the defense called Karen Crumbley, the sister of James Crumbley, to testify. She was the only witness the defense called to the stand. 

Oakland County Prosecutor Karen McDonald gave her closing argument and said that James Crumbley needs to be held responsible for the Oxford High School shooting due to his gross negligence. James Crumbley is accused of not safely storing the gun away from his son or getting his son the help he needed for his mental health struggles. 

"James Crumbley is not on trial for what his son did," McDonald said. "James Crumbley is on trial for what he did and what he didn't do."  

Defense attorney Mariell Lehman argued that he was not aware that his son had access to the gun or was going to carry out the shooting. She also said the father wouldn't have known what the shooter was writing in his journal or in text messages to his friend. 

Testimony in James Crumbley trial 

During the trial, the prosecution called several witnesses to testify. Most individuals called to the stand also testified during Jennifer Crumbley's trial. 

The first person called to testify was Molly Darnell, a teacher at Oxford High School who was injured in the shooting. She testified about how she made eye contact with the shooter before he shot her. 

The shooter's school counselor and the former Oxford High School dean of students both testified about meeting with James and Jennifer Crumbley and their son the day of the shooting, and detectives who responded to the scene of the shooting testified about searching the Crumbley parents' house and searching for the parents after charges had been issued. 

Assistant principal Kristy Gibson-Marshall testified talking to the shooter and witnessing him being taken into custody. Gibson-Marshall said the shooter didn't say anything and turned his head away from her.

Luke Kirtley, the owner of a coffee roasting business, testified about how he called 911 after he saw James Crumbley's car. 

The parents were found in an art studio in the same building as Kirtley's business. 

A Detroit police officer was the only person the prosecution called to testify that they didn't call to testify in the trial of Jennifer Crumbley. 

On Friday, Detective Sgt. Joe Brian with the Oakland County Sheriff's Office testified that speaking with James and Jennifer Crumbley on the day of the shooting. A video presented during the trial showed James Crumbley telling Brian he called police after hearing that there was an active shooter at the school where his son was a student and finding his gun missing.

David Metzke is a member of the department's SWAT team and discussed responding to the industrial building and locating the parents in the art studio. He was recalled to testify on Wednesday and said that he reviewed surveillance footage after finding the parents and said that James and Jennifer Crumbley did not leave the premises of the building after arriving; they had only stepped outside to smoke.

Officials react to James Crumbley guilty verdict

On Thursday, Oakland County Sheriff Mike Bouchard issued a statement following the verdict:

"As I have said at each step of these legal proceedings, my first thoughts are always with the families of the victims and the community so terribly impacted by this tragedy. You have my unwavering support. I know that these proceedings are not a re-opening of a wound, it is tearing wider a wound that has yet to heal. Each time my staff re-lives that terrible day in that school through their testimony, I can see the anguish in their faces. As this is the last criminal trial, I pray in the days ahead there will be less traumatic moments and more peaceful ones.

"The unconscionable actions of a troubled son and the inexplicably tragic inaction of two adults to exercise even the most basic responsible parenting for their son forever changed four families and the Oxford community. If you're very first thought when you hear about an active shooter at your child's school isn't, 'Is he OK?' but to worry if your son is the shooter or to rush home to find out if the gun you irresponsibly left unsecure is still there, then you should've done something in advance. There were so many inflection points where they could've changed the course of events, including when they refused to bring their child home on the day of the shooting.

"James Crumbley now stands guilty of involuntary manslaughter – joining his wife and son as convicted felons – in the deaths of four Oxford High School students. I applaud and thank the jurors for reaching a fair and just verdict in what was surely a difficult and emotionally draining experience for them. I'm also grateful for the prosecution team and my investigators who worked tirelessly on this case."

Statement from Oakland County Executive Dave Coulter:

"Another guilty verdict does not bring back Madisyn, Tate, Hana and Justin, but this is justice for the families and community - and for that I am grateful. I am also grateful for the dedicated efforts of Prosecutor Karen McDonald and her team on this groundbreaking case."  

Congresswoman Elissa Slotkin issued the following statement:

"This is a historic moment in the fight against gun violence, & also I hope a moment that brings relief for Oxford. Thank you to everyone who testified in these cases, & to the families of Madisyn, Tate, Justin, & Hana for their continued courage.

"As they said tonight, there is much more work to do to protect our kids from gun violence, but their resolve has ensured that justice was served.

"It's also important to thank [Prosecutor Karen McDonald] and her office, who have worked tirelessly on these cases for over two years. They felt the Oxford story in their guts like all of us, and they took action, even when others may not have pursued something so groundbreaking.

"Michigan law now reinforces the precedent these cases and the courts have set here: If you have an unsecured weapon in a home with children, and one of them uses it to commit a crime, you can be charged and held accountable."

In:
• Oxford High School shooting
• Oxford High School
• James Crumbley

Sara Powers

Sara Powers is a digital producer for CBS Detroit. Sara covers local news, often focusing on crime, politics, entertainment and historical events for our "This Day in History" series.