(CNN) -- New Hampshire authorities have ruled that the death of an 11-year-old girl, whose body was discovered in a river near her home a week after her disappearance, was a homicide.
Senior Assistant Attorney General Jane E. Young said in a statement released Thursday that the medical examiner has also determined what caused the death of Celina Cass, but "that result is not being made public at this juncture."
"The premature public disclosure of Cass's cause of death could have an impact on the integrity of the investigation in a negative manner," Young said in a statement. "The investigation into the facts and circumstances of Celina Cass's murder remains active."
The ruling comes a little more than seven weeks after Celina's body was found by divers searching the Connecticut River, just a mile from her home in West Stewartstown, on the Vermont border in northern New Hampshire.
She was last seen in her room, at her computer, around 9 p.m. on July 25, according to police. CNN affiliate WMUR reported that her parents told authorities the girl was gone when they went to wake her up.
A frantic search ensued, with teams searching "by air, by land, by water," Young said at the time, while friends and loved ones posted fliers bearing her picture in neighboring towns around.
Between her disappearance and the discovery of her body on August 1, authorities received hundreds of tips in their investigation.
Celina was a very good girl," her father, Adam Laro said afterward. "She was very kind, considerate. I guess you could say an everyday child that loved ... being in life," he said.
"I have no fingers to point Laro said in an interview on HLN's "Nancy Grace." "I hope there will be some answers, that's what I'm asking."
The medical examiner's office completed its autopsy on August 2, but a ruling and cause of death would not be made final until toxicology reports, which can take several weeks, and further investigations were completed.
CNN's Nina Golgowski and Chuck Johnston contributed to this report.