i really dont know, and a lot of my thinking is based on all the things ive read on other forums, theyve clouded my thinking, but currently, in my opinion and all allegedly, im thinking he knew who sm was, had seen her on runs, around town and remembered her from school, she was a local, she may have acknowledged him whenever they passed on the track, he may have become obsessed with her and on the morning he was walking through to get his car she ran past, smiled hello at him and on impulse he decided to assault her, she fought back and he killed her, taking videos of her body etc, he didnt want the body in his work vehicle so either got his friend to meet him with his beat up old vehicle and he put her in the boot, or he went and got the keys and did it himself, drove around with the body for a couple of days and took her to an isolated body of water he was familiar with, or less likely dumped her in an area where the fires were burning, i think he boasted to his friends or hinted at what hed done, think he possibly told his gf or she saw the video on his phone, she went to police and if the friend whos car he used was a witness, hes also helping police, i think he had a sad childhood with possible bullying or other abuse, i dont think children are born monsters they are made imo