More than a dozen state and federal investigators actively probe the suspicious death of a northern New Hampshire girl whose body was recovered from the Connecticut River Aug. 1 after an extensive seven-day search.

“We are working this case diligently in order to determine the facts and circumstances around her suspicious death,” Senior Assistant Attorney General Jane E. Young said Thursday.

Celina Cass, 11, was last reported seen alive inside the West Stewartstown home she shared with her mother, stepfather and sister on July 25. Divers recovered her body about a half-mile from her home on Aug. 1.

The Medical Examiner’s ruling on cause and manner of her death are pending results of toxicological tests and further criminal investigation.

Prosecutors called her death suspicious based on the condition of the body in and out of the water. Several media have reported the body was wrapped in a blanket when divers found it near a hydroelectric dam.

To date, no one has been taken into custody, Young said.

State police from New Hampshire and Vermont, the FBI, investigators and attorneys with the state Attorney General’s Office, state forensic laboratory technicians and specially-trained computer forensic experts are among those working on the case, Young said.

Investigators have reviewed and categorized an estimated 539 leads received so far on the case, Young said.

“New information continues to come in as recently as the last few hours,” she said.

Young urged anyone with information to contact New Hampshire State Police at Troop F barracks at 603-846-3333.

Toxicological testing on blood samples are being analyzed by a Pennsylvania laboratory. Young said it may be weeks before those tests are complete.