BOSTON (CBS) – 11-year-old Celina Cass was wrapped in a blanket when she was found dead in a river earlier this week, WBZ-TV’s Karen Anderson has learned.

The Associated Press reported Wednesday that authorities took away a silver pickup truck that had been parked near Celina’s home as the investigation intensifies.

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Meanwhile, an autopsy Tuesday failed to show how Cass died, so toxicology tests are underway.

It’s a lack of answers that’s frustrating to the young girl’s father.

“I’d like them answered, but if they can’t answer them, I may have to go without and that’s going to be hard to live with,” Celina’s father, Adam Laro told WBZ-TV’s Sera Congi Wednesday.

WBZ-TV’s Sera Congi reports.

Celina’s body was discovered in the Connecticut River Monday, about a quarter mile from her home in West Stewartstown, New Hampshire. She was last seen a week earlier in her home at her computer.

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Investigators returned to the river Wednesday, looking for more clues. It’s a search Celina’s father hopes will lead somewhere.

“She’s not the type to go off and just even go swimming without telling somebody. To find her in a river like that is shocking,” said Laro.

WBZ-TV has learned investigators are questioning Celina’s stepfather Wendell Noyes, but he has not been cooperating. Noyes was checked into a mental hospital in Concord on Wednesday.

Laro said Noyes seemed odd, but he never had any problems with him.

“When I went over there, he always treated me with respect. He always was decent to me,” said Laro, who added that he didn’t have concerns about his daughter living with Noyes.

Laro said he has not heard from investigators.

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The New Hampshire attorney general’s office is not releasing much information. Officials there said they have to protect certain facts, in case arrests are made.