This scenario makes a lot of sense. I've always felt that DP knew he couldn't let Stacy leave him with the knowledge she had in regards to Kathleen. He planned on doing away with Stacy, but didn't plan on doing it on a weekend with the older boys and neighbors home. I think he would have done it on a weekday and away from home - no witnesses.
I think DP killed Stacy in a rage on Sunday, Oct. 28th, and he was then caught in the worst possible circumstances, with the the children in the house and neighbors home. He had to get the body out of the house before the children found the body or before Stacy's family became suspicious.
Cass said she started calling Stacy in the early afternoon and got no response. She became increasingly alarmed. She went to the Peterson home about 11:00pm, saw that both the Denali and Stacy's car weren't there. One of the boys answered the door, saying that his dad wasn't home - that his mom and dad had an argument and Stacy left and his dad was out looking for her.
Later, Cass called Drew's cell phone and when he answered it he was out of breath and Cass heard the sound of car keys. She asked where he was and he said he was at home.......but Cass was sitting in her car near the Peterson house and could see that DP's car wasn't in the driveway.
In the wee hours of the morning, Cass and her boyfriend, Bruce, saw that both the Denali and Stacy's car were in the driveway of the Peterson home, and Bruce called Drew, who told him that Stacy had left him and she called and told him her car was at the airport and he had gone and brought it home.
It was at that point that Cass went to the police to report Stacy missing.
When Cass first called Drew, when he was out of breath and she heard the sound of car keys............he could have been out disposing of Stacy's body in the woods.