Authorities said Monday there appears to be no connection between Celina Cass, the Coos County 11-year-old murdered 17 months ago, and Israel Keyes, a serial killer whose victims included a couple in neighboring Vermont. Keyes was found dead in his Anchorage, Alaska, jail cell Sunday.

Keyes has been implicated in the disappearance and believed murder of an Essex, Vt., couple in early June 2011, nearly two months before Cass was reported missing from her West Stewartstown home and then found a week later submerged in a Connecticut River impoundment.

Keyes, who was awaiting trial in the random abduction-murder of an Anchorage woman in February, also disposed of her body in water, using a chain saw to cut through ice and then slip her body into a lake outside of Anchorage.

A federal prosecutor in Alaska told the New Hampshire Union Leader that Keyes, 34, was not believed to be in New Hampshire during Cass' late July 2011 disappearance. Assistant U.S. Attorney Kevin Feldis said investigators tracked Keyes' travel through credit cards, plane tickets and rental cars.

Records show he was in Alaska when Cass disappeared in late July.

"Our investigation indicates he was not in New Hampshire at that period of time," Feldis said.

Feldis said Keyes talked to investigators about several murders, and investigators believe he is responsible for four in Washington, one in upstate New York, the Vermont couple and Samantha Koenig, the 18-year-old Alaskan woman murdered in early February. He said Keyes never mentioned the Cass murder in his discussions with investigators.

He said authorities believe Keyes is responsible for more than seven murders.

"That's one of the tragedies here. We may never know what Israel Keyes did and may never know all his victims," Feldis said.

In New Hampshire, homicide prosecutor Jane Young said "our investigation into Celina's murder continues, and that death (of Keyes) does not impact the course of our investigation." She said state police did look into the possibility of Keyes involvement in the Cass murder after national news reported his connection to the disappearance of the Vermont couple, Bill and Lorraine Currier. Their bodies have not been found.

In January, New Hampshire authorities empaneled an investigative grand jury and called several witnesses involved in the Cass case, including people who were at the family's West Stewartstown home on the night of her disappearance. Nothing publicly has come of the grand jury work, and Young said she is barred from discussing grand jury proceedings.

She said leads still surface in the case, and investigators are reviewing past witness statements.

"There's not a week that goes by when I don't have contact with state police (about the Cass murder)," Young said. Asked if authorities have a suspect, she said, "At this juncture, we are not poised to make an arrest."

Before they can make an arrest, police need to assemble enough credible, admissible evidence to prove guilt, she said.

mhayward@unionleader.com