OMG.
We had a case in Alberta pretty much the same. The daughter was 12(!) and dating a 21 year old, and when her parents told her to call it off, the two of them murdered the entire family, and then sat on the lawn and had a picnic.
I might have hated my parents with a passion on occasion, but I would never have contemplated killing them. What the hell is wrong with these kids? And then the bleeding hearts will get in there and cry about how they're just "childdddddren" and "didn't understand what they were doing ..." and say they should be out of jail in two years.
BS to that. Lock them up and throw away the keys.
I also feel sorry for the dog...