The tragic 11-year-old's body was found dead on Monday, almost a week after her mysterious disappearance, but detectives are still trying to work out how she died.
As part of their investigation they have taken the truck, which neighbors said was used by her stepfather Wendell Noyes, who was reportedly taken to hospital hours before the youngster's body was found.
In the past he has received treatment for mental illness and was reportedly involuntarily committed to a mental institution and diagnosed with schizophrenia in 2003.
Officers remained tight lipped on why they were taking the truck, but it's thought they maybe searching for DNA or other clues in the vehicle.
New Hampshire Senior Assistant Attorney General Jane Young said has confirmed that an autopsy failed to determine how the girl died and further toxicology tests and more investigations were needed.
But she maintained the death was considered suspicious.
Cops are continuing to comb the river which divides Vermont and New Hampshire, near where Celina's body was found, while crime scene technicians said they were doing computer-aided diagramming to give them a precise electronic image of the area.
One of them said: "We always do a thorough job but because of the sad nature of this case, everyone is doubly determined to find out what happened.
Five hundred tips were received and the FBI offered a $25,000 reward for information leading to her and to the arrest and prosecution of anyone responsible for her disappearance.