Detectives investigating the Josh Powell case believe he may have left behind some information about Susan Powell's disappearance hidden in computer files, but they don't have the expertise to find it, KIRO 7 Eyewitness News reported.

Detective Gary Sanders of the Pierce County Sheriff's Department said Josh Powell was good with computers and "a very calculated individual."

Sanders said a search last August of the home where Powell lived with his father revealed nothing about Susan Powell's fate, but it did provide insight into Powell's personality.

"He kept birthday cards all categorized. He had bills categorized from years back, and I think that's just kind of his personality," Sanders said. "He was very meticulous about what he did."

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Investigators said precision played into Josh Powell's final plot to kill his two sons and then himself.

Sanders said Powell studied the combustible properties of gasoline and determined how much he'd need to explode his home in Graham.

Then, he meticulously settled his finances, "sending notices to cancel all his utilities, shutting off Comcast -- all those things," Sanders said.

Next, Powell brought two 5-gallon cans of gas inside the home. When his sons arrived for their visit, he attacked them with a hatchet, splattered one can of gas around the house, and sat on the second one and ignited it, police said.

"It was calculated," Sanders said.

Sanders said he believes Josh Powell was just as calculated about Susan Powell's disappearance.

He said Josh Powell was a computer programmer who knew how to encrypt files and likely filed away crucial pieces of information.

"But they're hidden within hard drives or stuff, where we'll never find them," said Sanders.

Sanders said Powell staged the Graham home to look like he lived there even though he was spending more time at his father's home in Puyallup.