Willis Goodale pleaded guilty Friday to one count of second-degree manslaughter, three counts of second-degree assault with a motor vehicle and one count of driving under the influence of alcohol or drugs in connection with the March 2012 crash that killed a Norwich firefighter and seriously injured his two young sons and the driver of a third vehicle.

Norwich Firefighter Benjamin De Mond, 33, was killed and his two sons, Alexander, then 6, and Nicholas, then 4, suffered broken bones and internal injuries in the March 9, 2012, crash on Interstate 395 in front of the state police Troop E barracks. The driver of the third car — Andrew Crouch, 59 at the time, of Montville — also suffered multiple injuries.

Goodale, 52, formerly of Groton, is being held at the Corrigan-Radgowski Correctional Center in Montville and will be sentenced Oct. 1 to 15 years in prison, suspended after eight years served, followed by five years of probation that will include several restrictions, Judge Kevin McMahon told Goodale Friday.

Attorney Mark Griffin, who represents the De Mond family victims and Crouch in both the criminal case and a civil wrongful death lawsuit, told the court Friday that the survivors will make a detailed statement at Goodale’s sentencing. Griffin, of the Watertown law firm D’Amico, Griffin and Pettinicchi, said the victims did not object to the proposed sentence.

Following Friday’s plea session, Griffin said he did not ask family members to attend the court appearance Friday to spare them from having to go through the painful process twice.

Goodale, wearing tan prison attire, pleaded guilty to each charge and answered McMahon’s questions but did not make a statement in court Friday. Assistant State’s Attorney Christa Baker said the victims’ families were consulted on the plea deal and proposed sentence, and Goodale sent letters of apology to the families. She said Goodale has been cooperative throughout the process.

He was initially charged with second-degree manslaughter, first-degree reckless endangerment, three counts of second-degree assault with a motor vehicle, driving without insurance, failure to maintain proper lane, improper use of emergency turnaround and improper turn.

During the plea session, Baker read a detailed account of the crash, the immediate aftermath and the injuries suffered by all the victims. She called it “a terrible accident with horrible injuries.”

Baker said Goodale admitted he was living in his Jeep Cherokee parked at the Mobil gasoline station and convenience store on the southbound side of I-395 for the two weeks leading up to the crash. She said he had been “down on his luck.” On the day of the crash, he purchased snacks and grocery items at the store, charged his cellphone there and also consumed several drinks containing vodka and orange juice prior to attempting to drive from the highway rest stop.

Goodale attempted to cross the southbound lanes of I-395 to enter the emergency vehicle turnaround in the center median when De Mond swerved and lost control of his Nissan Maxima in a failed attempt to avoid crashing with the Jeep.

De Mond’s car was propelled into the emergency turnaround and entered the northbound travel lane, where it collided head-on with Crouch’s car, causing that car to roll over. De Mond’s car hit another vehicle driven by Albert Fisher of Lisbon.

Baker said Goodale initially got out of his vehicle and entered De Mond’s vehicle and said he was sorry and didn’t mean to cause the crash. When emergency personnel arrived, Goodale was seen walking back toward his vehicle. Police observed he was unsteady on his feet, and asked him to take a field sobriety test. His blood alcohol level was three times the state limit of 0.08, Baker said.

She said Benjamin De Mond suffered multiple fatal injuries. Alexander De Mond suffered six broken ribs, chest, lung and liver injuries, severe fractures to an elbow and ankle that required surgery and screws, and a broken shoulder bone. Baker said he still suffers headaches, anxiety and depression and has nightmares.

Nicholas De Mond suffered an eye injury and other immediate injuries, and still experiences migraine headaches, nightmares, anxiety and depression, Baker said.

Crouch too suffered a broken ankle, a fractured bone in his back and suffers from depression and anxiety.

Baker said the combined monetary medical costs, losses and lost income calculated for Benjamin De Mond totaled $2 million. Griffin later added that the figure did not include pain and suffering caused by the crash.

Griffin said he will give a presentation at the Oct. 1 sentencing on the extent of the victims’ injuries and their losses.

c.bessette@theday.com