Allan Shyback is charged with second-degree murder and committing an indignity to a body.
Investigators believe her remains had been in the house for two years. Her relatives in the Longview area had reported her missing in the fall of 2012.
The couple’s children, aged five and seven, are safe, police said.
Dawn Schneider, Mitchell's longtime friend, said she feels badly for the children.
“I kind of started crying because we didn't know what happened the night before and then we woke up and we're seeing everything all of a sudden hearing her name was like of like, ‘Oh my God.’”
Schneider said she met Mitchell in high school.
“She was nice to everybody kind, she was just a very nice and sweet person, not mean, not mean at all, nice to everybody.”