Michigan school officials had the legal grounds to search alleged shooter Ethan Crumbley's backpack and locker but did not do so, Oakland County prosecutor Karen McDonald told CNN Monday.

Catch up quick: Crumbley has been charged with numerous felony counts related to terrorism and murder after opening fire at Oxford High School, killing four students and wounding seven other people.

• His parents, James and Jennifer Crumbley, have been charged with four counts each of involuntary manslaughter tied to their alleged purchase of a handgun for their son.

Background: Days before the shooting, a teacher caught the suspect searching for ammunition on his phone during class.

• On the day of the shooting, a teacher found a drawing made by the suspect that contained a picture of a gun and a figure appearing to have been shot twice. Crumbley's parents were called to the school and told to put their son in counseling within 48 hours.

What she's saying: McDonald answered "yes" when asked if the school had legal grounds to search the suspect's backpack and locker.

• When asked if the school did so, McDonald said, "No. I mean, we don't know exactly if that weapon was in his bag, where it was, we just know it was in the school and he had access to it."
• Asked if staff members at the school might be prosecuted, McDonald said, "We haven't ruled out charging anyone."
• A spokesperson for Oxford Community Schools did not immediately respond to a request for comment.

"I'm certainly not suggesting that parents should be criminally prosecuted for any bad act of a child," McDonald added. "But in this case, you can't possibly look at their actions and say that they didn't have reason to believe that there was real concern about a violent act."

Go deeper: Michigan AG offers to probe school district's actions ahead of shooting