HICKORY, N.C. - Investigators cast doubt yesterday on accounts given by the father and stepmother of a missing 10-year-old whose battles with bone cancer left her with a prosthetic leg and hearing aids in both ears.

A search warrant revealed yesterday that police dogs had detected the smell of human remains in cars belonging to the couple. Hours earlier, the police chief said that investigators were having trouble finding anyone outside the household who had seen Zahra Clare Baker alive in the last few weeks.

The warrant, filed in a Hickory court, did not indicate that police had found any remains in their search Sunday. It said that the dogs detected the smell on a sedan and SUV.

The couple had told police that they discovered that the girl was missing on Saturday, and that one of them had seen her sleeping in her room hours earlier. Yet Hickory Police Chief Tom Adkins said that investigators were having difficulty with that account.

"We don't know the last time anyone saw her," he said an afternoon news conference. "We're having a difficult time establishing a true time line."

When the search warrant was filed hours later, police declined to comment further but said that Adkins would issue a statement this morning.

Zahra's father, Adam Baker, said during a morning TV interview that it was possible that his wife could be involved in the disappearance. Elisa Baker was arrested Sunday on about a dozen charges, including passing bad checks, unrelated to the girl's disappearance.

Adkins said that the father was cooperating with police but that Elisa Baker wasn't.

On Saturday afternoon, Adam Baker called to say his daughter was missing.

Zahra was described by family friends as shy but constantly smiling, in spite of her health problems. The stepmother could be short-tempered toward her, two former neighbors said.

"I just hope I can get my daughter back. I miss her so much," Zahra's father, Adam Baker, told ABC's "Good Morning America"yesterday.

The girl's stepmother told her husband that she last saw Zahra asleep in her bed at 2:30 a.m. Saturday.

The police chief said he wouldn't rule out any suspects, including Adam Baker.

Adam Baker, an Australian who met Elisa Baker over the Internet, was asked if he thought his wife was involved and said: "I wouldn't like to think so. On what I've heard so far, it could be possible."