Joshua Powell has claimed he took his two sons, 2 and 4, to the Pony Express Trail to camp in the family van at 12:30 a.m. Dec. 7, the day 28-year-old Powell was reported missing.
Now that police say he is not answering additional questions about that night, they have labeled him a "person of interest" in his wife's disappearance -- "not a surprise, given the events and his reaction to them in the past week," Gifford said.
Officers on Thursday barricaded and searched the Powell home, dusting for fingerprints and taking items out of the house.
Detectives also are seeking cell phone records, said Assistant Police Chief Craig Black. He would not say whose cell phone records police were seeking.
Susan Powell's phone was found at home, along with her purse and keys, after her disappearance, said Michael Gifford, who is married to Shelby and accompanied Susan Powell's father, Charles Cox, to Utah to help with the investigation.
"She would never leave her home without her ... cell phone, especially if her children were gone camping in the kind of conditions that they had gone camping," Michael Gifford said at Thursday's press conference, held at the Powells' hometown of Puyallup, Wash.
Capt. Tom McLachlan said the Powells' 4-year-old son, Charlie, told investigators the family did go camping, but McLachlan would not elaborate.
Joshua Powell has been caring for Charlie and 2-year-old brother, Braden, since their mother's disappearance. They have been staying the family of Joshua Powell's sister.
"He's always been a super father to them," Cox said of Joshua Powell. Cox has spoken in defense of his son-in-law during the 11-day search.
"There's no doubt in my mind that they're safe with him," he said at the press conference.
Shelby Gifford said the family had no indication that the Powells' marriage was abusive.
"If we felt like Susan was in danger, as a family we would have taken the steps to get her out of the situation," Shelby Gifford said. "Some of the things you're learning about this week, we're learning right along with you."
Susan Powell's friends have told various media outlets that they had been concerned about the health of the marriage, which had undergone financial and emotional strains.
On Wednesday, it was revealed Susan Powell, 28, kept a journal at work, according to several sources. Police refused to confirm whether they had the journal, citing a policy against discussing evidence.
Kirk Graves, the husband of Josh Powell's sister, told NBC's "Today" show Thursday that his brother-in-law could be controlling, and was an "interesting person" with a "different" personality.
Asked whether he thought his brother-in-law had something to do with Susan Powell's disappearance, Graves said he's avoided analyzing the question.
"Too many emotions, too many family members. I just pray no," he said.
West Valley City Police Chief Buzz Nielsen said while his officers remain suspicious of Joshua Powell's story, they are investigating other possibilities to explain Susan Powell's disappearance.
"If you focus your attention on any one area, you're going to miss something else," Nielsen said.
"We've got some members of the public that are calling in and chewing us out and saying, 'Why don't you arrest him?'"
Nielsen said since national news media have begun reporting the story, people from across the country have called in with tips about the Powell family or ideas about where Susan Powell might be. Detectives are following up on those calls, he said.
"We've got a lot more to do."
Forensic scientists spent much of their time Thursday inside Powell's house, removing four large paper bags of evidence and several vials and swabs. An investigator spent time on the front porch, analyzing the front door and window. Detectives and forensic scientists spent just over three hours in the house.
It was unclear if Joshua Powell was in the house at the time.
Nielsen did not expect any more search warrants for the home.
"I think we're done going back to the house."
Relatives who answered the door at the home of Joshua Powell's mother, Terrica Powell, declined to comment on the Cox family's press conference or anything else about the case.
Susan Powell's friends and family have set up a Facebook page and distributed fliers to spread word of her disappearance. Among those helping the family are Damon Talbot, who set up the Destiny Search Project, Inc., after the murder of Destiny Norton in 2006, and Ed Smart, whose daughter Elizabeth spent nine months in captivity before being found in 2002.
Afternoon, Dec. 6 » Neighbor JoVonna Owings dropped by the Powells' home Sunday afternoon to visit with Susan Powell. The family had pancakes for dinner. Susan, who was feeling ill, lay down for a nap about 5 p.m. Owings left, as did Joshua Powell, who said he was taking his two sons sledding.
8:30 p.m., Dec. 6 » A neighbor saw Joshua Powell as he returned home and pulled into his garage.
Midnight to 12:30 a.m, Dec. 7 » Joshua Powell says he left home with his two sons to go camping at Simpson Springs in the west desert, while Susan remained at home.
9 to 10 a.m., Dec. 7 » The Powells' day care provider became alarmed when the couple failed to drop off their sons on schedule and she could not reach either parent by phone. She contacted Joshua Powell's mother and sister, who called police after they could not locate the pair. Police broke into the Powell home but found no one there.
Evening, Dec. 7 » Joshua Powell and his two young sons returned home between 5 and 6 p.m. He was taken to the West Valley City police station for questioning.
11 a.m., Dec. 8 » Charles Cox received a telephone call from Joshua Powell, who informed him Susan was missing and that he was about to be interviewed by police again.
Dec. 9 » Police served a search warrant on the Powell residence and removed boxes, bags and a computer.
Dec. 10 » Law officers searched the Simpson Springs area where Joshua Powell said he camped with his sons but found nothing.
Dec. 14 » Joshua Powell hired defense attorney Scott C. Williams. He skipped a third interview with police.
Dec. 15 » Joshua Powell provided a DNA sample to police.
Source: Salt Lake Tribune, West Valley City Police Department, Kiirsi Hellewell, Charles Cox, media reports