Detective Ed Troyer says the search is expected to last all day Sunday.
Powell was the husband of missing Utah woman Susan Powell. He attacked his 5- and 7-year-old sons with a hatchet last Sunday and then ignited the house in a gas-fueled inferno.
Some investigators have called the act an admission of guilt in his wife's death, but they're still looking for evidence on that front. They also located a storage locker where Powell had stashed a comforter that tested positive for the presence of blood in an initial test. Further lab tests are pending.
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