Thirty thousand dollars will be offered as rewards for any information that leads the authorities in solving the mysterious death of Celina Cass, a state prosecutor has announced.

Celina Cass, a 11-year-old New Hampshire girl, was found dead in the river near her home on August 1, after nearly a week of going missing.

Cass' body was found in the Connecticut River near a hydropower station in West Stewartstown, a New Hampshire by a dive team from the New Hampshire Fish and Game Department - a week after the authorities began their search.

Based on what we have seen visually we are treating it as suspicious, said Jane Young, a senior assistant attorney general from New Hampshire.

Cass was last seen at home before her computer at about 9 p.m. local time on July 25. But when her parents woke her up, she had disappeared, authorities said.

The autopsy result is inconclusive and it couldn't discover the cause of Cass' death.

However, the investigators believe there must be some people, who witnessed something or have some information helpful for the case.

“Even the smallest observation could provide a piece of the puzzle necessary in solving this tragedy,” Young said.

The FBI has offered $25,000 and $5,000 donation from an anonymous source as reward for information that leads to solving Cass' death.

According to Young, the anonymous donor is a “concerned citizen”, who lives in the North Country, and has donated the $5,000 for the case “because of how devastating it's been to that community.”

“I've had people call as far away as New Mexico saying they want to donate to this,” Young continued.

Currently many witnessed are being interviewed and the authorities are still investigating Cass' death.

Anyone with related information should contact New Hampshire State Police at 603-846-3333. Anyone, who wants to make donation for the case as the public reward should contact Susan Small at Northway Bank in Gorham at 603-466-5467.