Powell was last seen in Utah in December 2009, and information from a newly released search warrant suggests detectives suspected from the start that her husband Josh was involved in her disappearance.
Josh Powell and the couple's two children died in a Puyallup, Wash., house fire and explosion in February.
Appearing on the NBC program "Today," Chuck Cox, Susan's father, said, "The bottom line is, she stayed too long [in the marriage]. We knew they had trouble, and she thought she could handle it, and she stayed too long."
The search warrants, unsealed Friday in Pierce County (Wash.) Superior Court, mention that her blood was found on a tile floor inside their home, as well as two fans blowing directly on a couch that appeared to have been recently cleaned.
The search warrants were released in a separate case involving Steven Powell, Josh Powell's father, who was charged in September with voyeurism and child pornography possession. The documents suggest Utah police suspected Josh Powell killed his wife but did not charge him.
"There is direct evidence, there is circumstantial evidence, there is motive. There is everything but the body," Pierce County prosecutor Mark Lindquist told NBC News.