A Michigan jury found Jennifer Crumbley, the mother of the Oxford High School shooter, guilty of four counts of involuntary manslaughter.
The jury reached its unanimous verdict after 10 hours of deliberation. Ms Crumbley sat in court, unemotionally, as the verdict was read.
She had pleaded not guilty. The 45-year-old’s husband, James Crumbley, is being tried separately in March.
In December, Ethan Crumbley was convicted of killing four of his classmates and injuring seven others on 30 November 2021.
The prosecution has accused her of neglecting her son’s “downward spiral” and making a gun accessible in their home.
The defence rested its case on Friday after the defendant took the stand. Ms Crumbley’s attorney delivered strange closing arguments, in which she compared herself to Ms Crumbley as “messy” working moms.
The prosecution argued that Ms Crumbley could have taken “tragically small” steps that could have prevented her son from shooting up his school. The prosecutors mentioned that the mother bought her son a gun days before the shooting, recognized that he was “acting depressed” and spent a lot of time alone.
The trial has been chock-full of revelations: an extramarital affair, a shocking admission, and a Taylor Swift reference.
She will be sentenced on 9 April.