koppel wanted to set a new date for their wedding, but lily wasn't interested. oppel returned home. he admitted to police that he was drunk. the fight with his ex-fiance only added to the anger and bitterness he felt toward adrienne. so he took revenge. prosecutors believe koppel stood outside the house where adrienne lived with her two roommates, casing the place and smoking cigarettes. he used a knife to pry open the window and accidently dropped the packet of zip ties on the floor with his dna. leslie's bedroom was the first room at the top of the stairs and he killed her first. he then went across the hall to adrienne's room. she fought back aggressively. at some point, he cut his hand and bled profusely as he rushed out of the house. >> at that point, based on what he's told us, at least, that he took his clothing and burned them in a fire pit that he had in his back yard, went back to sleep. and then the next day went to lily's house to console her. after lily called him to tell him that adrienne had been attacked. >> no one knows why koppel spared lauren.