AUGUSTA — A Gardiner man is on trial in Kennebec County Superior Court, accused of beating his longtime girlfriend so badly at their home last October that she suffered fractured ribs and a collapsed lung. Two days later, as they were driving south on Interstate 95, he allegedly stabbed her in the thigh with scissors.

David F. Dineen II, 50, is charged with three counts of aggravated assault and one count of domestic-violence assault, all of which allegedly occurred Oct. 11-13, 2012.

Charges of kidnapping and criminal restraint from the same time frame were dismissed earlier.

In his opening statement Wednesday, the prosecutor, Deputy District Attorney Fernand LaRochelle, said police questioned Dineen after his girlfriend was interviewed at the hospital.

“He told police he had a tussle with her,” LaRochelle told the jury of four men and 10 women, adding that “tussle” was Dineen’s word.

He said Dineen had confronted his girlfriend in the basement of their home after learning she had been cheating on him.

LaRochelle said the girlfriend sought help from her mother two days after the initial event. In the interim, LaRochelle said, Dineen took the woman and two children to view Mount Katahdin, and then the four stayed overnight at a hotel in Bangor.

The argument resumed there and on the way home, LaRochelle said, resulting in the girlfriend being stabbed in the thigh with scissors as Dineen was driving.

Dineen pleaded not guilty, and his attorney, Walter McKee, told jurors Dineen’s girlfriend hand-wrote a statement two weeks ago saying that she had lied previously about the events and that the injuries occurred after she fell down the basement stairs at their home and after she tried to stab Dineen as he was driving back to Gardiner.

“She is trying to turn over a new leaf,” McKee said. “She is now drug-free and coming forward. Your common sense will tell you David Dineen is not guilty of the crimes he is charged with.”

Dineen’s trial is expected to resume at 8:30 a.m. today.

Betty Adams — 621-5631[email protected]Twitter: @betadams