"She's been gone for an entire week. I don't believe there can be any, very much hope left," a tearful Kiirsi Hellewell, Susan Powell's best friend, told ABC News this week. "I'm trying to stay busy and not think about it. But I don't see how there's any way she can still be alive."
Joshua Powell told police his wife didn't go camping with them because she was feeling sick.
Cox said it's not unusual for his son-in-law to get a late start.
"It was believable," Cox said of Powell's story. "It was unusual, but believable to me."
But Hellewell said she talked to Susan Powell the day she went missing and she wasn't sick. Police told ABC News they couldn't verify Joshua Powell's camping trip because snow had covered the spot where he said they went.
The West Valley City Police found Susan Powell's purse and keys in her bedroom and say there was no sign of forced entry at the house.
"She would never leave her children, and she would never leave without contacting anybody," Hellewell said.
Susan Powell's friends told ABC News that although the couple openly had discussed marital and financial problems in the past and at one point were considering divorce, they had made a real effort to reconnect.
They both had good jobs, Hellewell told ABC News, and Joshua Powell had begun going back to church.
Cox previously had criticized the speculation about his son-in-law's possible involvement.
"I don't see him as capable of harming her," Cox told the Salt Lake Tribune this weekend. "I'm kind of concerned that all the focus is on him."
Police officials interviewed Joshua Powell, as well as the couple's 4-year-old child, but walked away with more questions than answers, they told ABC News last week.
"He did give us a statement, and we're following up on all aspects of that statement," said Capt. Tom McLachlan, who called her disappearance "suspicious."
Anyone with information regarding the case can call West Valley City Police at (801) 840-4000.