responsibility, in getting that gun, letting their child have that gun or what they knew about the child who would know better than the parents. this is a new frontier in terms of imposing responsibility on people for these kind of mass shootings. >> what kind of challenge is it proving these charges? i mean, this is -- we've got a lot more to learn here now. >> yeah. it's difficult for prosecutors. you have to prove your case beyond a reasonable doubt. important to keep in mind the prosecutor does not have to prove that parents knew or intended, okay, he's going to go out and kill people or harm people. it's a lower bar than that. you have to prove what the parents did was inexcusebly rkless, criminal negligence, they created or contributed to a situation they should have foreseen could have been dangerous to somebody's life or someone's great bodily harm. that's a lower bar than what you think of as your traditional intentional murder, but yes, prosecutors will have to prove this case beyond a reasonable doubt.