The autopsy on dead 11-year-old girl from New Hampshire, Celina Cass, did not give any conclusive evidence relating to her death, investigators said late Tuesday.

New Hampshire senior assistant Attorney General Jane Young stuck to her earlier stance that police have not identified anyone as a suspect as yet. The investigating team is analyzing possible suspects and they have not ruled anyone in or out, Young said. However, she said one predictable angle in this investigation will be to investigate reported sex offenders in the area. The official line is that there are no "persons of interest" at the moment, and no arrests have been made.

Young assured that despite the sex predator angle the investigators are looking at, there was no need of any 'heightened alarm' in the community.

Investigators have not been able to determine where in the rive her body was eventually placed, but early clues seemed to have established that the date of her death, judged by visual evidence, matched with her reported date of disappearance.

The fact that her body was submerged in water for an unspecified number of days may have played a role in the autopsy being inconclusive, the investigators said, but they did not divulge how many days her body was in the Connecticut river.

Nor did they say what really the autopsy was able to find at all. Young said further details about the autopsy could not be made public as the priority was on protecting the "integrity of the investigation."

“The cause and manner are still pending ... [investigators] "are awaiting toxicology results and further investigation," Young said. "We are doing everything we can to have more definitive answers.”

Police are now waiting for the result of toxicology tests to unlock the mystery behind how Celina died and when. They can’t confirm or deny if the death was a kidnap and murder, or just an accidental drowning. A complete analysis of autopsy results, combined with the toxicology results will throw light into how she died, and this will be crucial in finding out who killed her.

Celina disappeared in the night of July 25. The last person to see her was her stepfather Wendell Noyes, who said she was playing on the computer when he saw her. When the family tried to wake her up the next morning, she was gone and there was no trace. Police said there was no trace of any force being used, and her friends said Celina was unlikely to go with a stranger on her own volition.

Local police and the FBI launched a massive search using air, land and water-borne resources, and her body was fished out from the Connecticut River, near a hydroelectric dam between Stewartstown and the town of Canaan, Vermont.

She was living with her older sister, mother and step father. Her biological father, Adam Laro, said she could not believe how anyone would hurt her. He said Celina was an “everyday child who loved being in life”. “That’s the thing that puzzles me ... I can’t see why someone would want to do that to my daughter. … She was very kind in spirit.” He said he had seen his daughter happy when he last saw her.

Meanwhile, Celina's step father, ex-Air Force member Wendell Noyes, has been in public eye thanks to his bizarre behavior on the day when Celina's body was retrieved from the river. He rolled on the ground face down, and an ambulance reportedly took him to the hospital. He was discharged on Monday, and was seen picking up cigarettes from a shop in town the next day.

It emerged that Noyes had a troubled past and that he had been medically discharged from the Air Force owing to mental illness.

He also had been arrested in 2003 for threatening an ex-girlfriend and was involuntarily institutionalized. But in this case, he was declared unfit to stand trial owing to his mental illness. However, the judge had noted that his mental illness posed "a potentially serious likelihood of danger to himself and others."