Griswold — Speed caused the December crash that killed four Griswold teenagers, according to a press release issued today by state police.

Investigators concluded that John Clapper III, who was driving the car, was speeding as he drove on Route 201. Clapper drove over a portion of the road at a speed that “caused the suspension to unload,” police said, at which point Clapper lost control of the car.

The vehicle, a 2007 Nissan Altima, slid sideways and struck a set of trees located off the southbound shoulder of the road, police said. When it hit the trees, the car upended, according to police, “causing the roof to strike the same set of trees that were struck at initial impact.”

Police concluded that Clapper, 16, was at fault, according to the press release. The investigation is closed and there will be no charges filed, state police said. Clapper, who had a learner's permit, was killed in the crash along with three of his friends.

Sativa Cornell, and Dillon Clifford, both 16, and Steven Szklarz, 15, were also killed. Joel Gallup, 16, was the lone survivor and continues to recuperate.

The single-car accident happened at about 4:30 p.m. on Dec. 7, 2010, along Route 201 near Route 138.

Three sets of parents have filed their intent to sue the town. Steven and Shirley Szklarz, co-administrators of the estate of Steven Szklarz, filed in June.

John C. Clapper Jr. and Roberta Clapper, co-administrators of the estate of John Clapper III, filed the notice on June 1. Gina Pelletier and Eugene Cornell, parents of Sativa Cornell, filed a similar suit May 18.

The lawsuits claim that "negligence and carelessness" by the town of Griswold resulted in the injuries and subsequent deaths that happened in the crash, which occurred after school let out for the day. The suit claims the teens involved had cut class.