Investigators trying to determine what caused the death of an 11-year-old New Hampshire girl have taken away a silver pickup truck that had been parked near her home.

On Wednesday morning, investigators were focusing their attention on the Stewartstown home of Celina Cass, whose body was pulled from the Connecticut River after an intense manhunt for the girl.

The fifth-grader had been missing for a week before her body was found in the river on Monday.  The girl was last seen the night of July 25 in her home where she lived with her mother, stepfather and 13-year-old sister. 

Jane Young, New Hampshire senior assistant attorney general, said Tuesday that investigators are waiting for further toxicology reports before making any determinations in the death of Celina Cass. Authorities are calling her death "suspicious."

Meanwhile, Jeanine Brady, a family friend and the employer of Celina's mother, says the girl's body has been turned over to the family and a service is being planned. Brady won't say where or when the service would be held. She says it will be private.

Young would not go into details about the initial autopsy results but said, "both the cause and manner of death are pending."

After an extensive search for the child -- which included help from the FBI -- divers discovered her body Monday morning near a hydroelectric dam that spans the Connecticut River between her hometown and Canaan, Vt., not far from the Canadian border. 

"We have made no determination on where her body was eventually put in the river," Young said on Monday.

Authorities have said there was no sign of a struggle inside the home, and there was no indication the girl ran away or that someone took her. 

"Based on what we have seen visually, we are treating it as suspicious," Young said.

Celina's father, Adam Laro, had described his daughter to Fox News as "shy but very friendly" and said he can't imagine she'd leave on her own.

"I can't picture why she would leave at night," said Laro, who was in the hospital when Celina was last seen. "She seemed to be happy where she was."

Her stepfather, Wendell Noyes, described her as a quiet girl who would not have left the family's three-story home on her own. Noyes, who reportedly has a history of schizophrenia, was taken by ambulance to a hospital Monday morning, though the reason for his hospitalization it not yet known. 

Young told FoxNews.com last week that authorities did not issue an Amber Alert for Celina because the case did not meet the criteria for one. Amber Alerts usually require a description of a vehicle or person the child was last with, Young said.

The girl's close-knit community held a candlelight vigil for the girl on Monday, just hours after her body was pulled from the river, the Boston Herald reports.

"She was a dream student," Jennifer Mathieu, who taught Celina in second and third grade, said of the girl. "If one of her friends was in a bad mood, she was the first to go over and try to cheer them up. She wanted everyone to be happy."

In the search for the tall, gap-toothed girl, investigators knocked on hundreds of doors and posted fliers with her photo throughout Stewartstown and nearby communities. Law enforcement agencies had set up a command post at the local school.

The FBI had offered a $25,000 reward for any information leading to Celina's whereabouts and an anonymous donor had added $5,000 to the reward. 

FoxNews.com's Cristina Corbin and the Associated Press contributed to this report.

Click for more on the disappearance of Celina Cass from MyFoxBoston.com