Authorities plan to resume excavating what they called a shallow grave in the central Utah desert in their investigation into a missing mother after a day of digging provided no clues, no remains and no progress.
Cadaver dogs discovered the location this week amid a renewed search for Susan Powell, and investigators declared they had found human remains earlier in the day Thursday.
But authorities later said that after digging into the site several feet down, they found no remains. Police said they assumed human remains would be found after cadaver dogs alerted on the spot.
"Right now, we haven't found anything except for these scents that these dogs are picking up," West Valley City Police Lt. Bill Merritt said Thursday evening. "We have not come across bones."
The excavation was set to resume Friday morning.
Earlier in the day Thursday, a Bureau of Land Management anthropologist was brought in to determine if the site was part of an ancient burial ground. The scientist later said it wasn't, but instead showed signs of recent disturbance.
"Shovel by shovel full," Merritt said. "Every shovel full that comes out is being sifted through. It's a painstaking process."
West Valley City Police Chief Thayne "Buzz" Nielsen said the area where the dogs indicated remains would be found was beneath what appeared to be a shallow grave covered with dirt.
"They have found what looks like a grave where the dirt has been shoveled and moved around a little bit," Nielsen said.
Police have been searching since Monday in the area near Topaz Mountain in Juab County for any clues in the disappearance of Susan Powell. The site is about 135 miles southwest of the location where she was last seen at her home in West Valley City on Dec. 7, 2009. It is also just about 30 miles south of where Powell's husband, Josh Powell, told police he took his two young children camping on the night his wife vanished. He told police he and their young sons _ then 4 and 2 _left his wife at home about 12:30 a.m. The 4-year-old confirmed the trip to police.
Josh Powell is the only person of interest in the case, but has never been arrested or charged. He has denied having anything to do with her disappearance and said he believes his wife ran off with another man.
Merritt said the discovery "fits in with what we've been looking for," but said there was a "50-50" chance they would find remains belonging to Susan Powell.
She was 28 when she was reported missing after she failed to show up for her stockbroker job.
The area where authorities are now working is in a rugged remote section of Utah's central high desert surrounded by grasses and sagebrush and punctuated by jagged mountains rising from the flat landscape. At the time of year Susan Powell vanished, it would have been bitter cold, the ground frozen, possibly even snow-covered.
Josh Powell was driving a minivan that night. Merritt said the site would have been difficult to reach in December but not impossible.
Meanwhile, officials from the U.S. Army's Dugway Proving Ground have contacted authorities about the possibility that any remains found might belong to Spc. Joseph Bushling, Army spokeswoman Paula Thomas said.
"We have no reason to believe it's him, but we're being diligent," she said.
Bushling disappeared May 8 from Dugway Proving Ground after telephoning a fellow soldier to tell him he was out of gas, cold and walking without shoes, according to authorities. A vehicle he was driving and his hat were later discovered south of Dugway roughly 20 miles away from where authorities are now searching for Susan Powell.
There have been numerous instances in the past two years where speculation swirled that Susan Powell's remains had been found.
The latest came in May when remains were discovered in the desert about 50 miles southwest of Salt Lake City. Authorities later said it was a young adult male.
In January 2010, a body was found about 40 miles outside West Wendover, Nev., but authorities eventually said it was a man's remains. Three months later, a woman's body was discovered about 12 miles outside of Twin Falls, Idaho. West Valley City police investigated the possibility that it was Powell but later said it wasn't. Local police later linked the bones to another missing woman.
In September 2010, a woman's remains were found on a Wyoming ranch. West Valley City detectives investigated but they turned out to be from a different missing person.
At the time, a spokeswoman for the Powell family told a Seattle television station police had called them "seven or eight times" about bodies that had been discovered.
"There really is no good outcome when the phone rings," Shelby Gifford said.
The case then appeared to stall until last month when investigators searched mine shaft-dotted mountains near Ely, Nev., and later served a search warrant at the Puyallup, Wash., home that Josh Powell shares with his father, seizing computers and journals.
Susan Powell's father, Chuck Cox, planned to be at the search site in the Utah desert on Friday.
The Powell family put out a statement this week urging police to release more details about what they were finding.
"With very little information available to the public, we can only hope that additional information is released quickly to minimize heartache to those of us who love Susan," it said. "In the meantime, we continue to hope for Susan's safe return."
Last month, the case turned salacious as family members on both sides sparred over accusations of sex and lies.
Josh Powell's family claims Susan Powell was sexually promiscuous, emotionally unstable and suicidal, accusations her family denies.
In yet another strange twist, Steve Powell, Josh's father, claimed he and Susan Powell were falling in love and even implied a sexual relationship had occurred.
Susan's family said the allegations are false, and that it was Steve Powell who initiated unwanted sexual advances.
The feuding between the two sides got so heated that a court commissioner in Washington state last month ordered Chuck Cox and Josh Powell to keep 500 feet apart.
Associated Press writers Brian Skoloff, Josh Loftin and Lynn DeBruin in Salt Lake City, Eugene Johnson in Seattle and Ted S. Warren in Puyallup, Wash., contributors to this report.