An Idaho mother who drove her SUV off a cliff, killing herself and her three children last year, did so deliberately, authorities announced Friday. 

Noel Bankhead, 40, drove a Land Rover off a 50-foot cliff with her two daughters and son inside on June, 2, 2016. The vehicle sank in 40 feet of water in Lucky Peak Lake. 

Read: "Dad 'Deliberately' Killed Himself, Wife and 3 Kids by Driving SUV Into Lake: Cops

The deaths have been ruled triple homicide-suicide by the Ada County Coroner’s Office, police said. 

Police found the bodies of Bankhead and her children, Anika Voermans, 13, Logan Voermans, 11, and 8-year-old Gwyneth Voermans when they recovered the vehicle from the water. 

Police determined the cause of death for the four was drowning with blunt force trauma.

Witnesses said Bankhead was driving on a state highway when she veered off it. She reportedly positioned her vehicle toward the cliff and accelerated. 

The vehicle she was driving did not have mechanical problems, police said.  

The sheriff’s office relied on witness statements, and the absence of skid marks to determine that Bankhead intentionally drove off the cliff, the New York Daily News reported. 

Read: Motorcycle Goes Off Cliff in Terrifying Moment Caught on Video: 'I Thought He Was Dead'

Toxicology tests found no medication or alcohol in Bankhead’s system, reports said. 

Bankhead reportedly went through a divorce about two years before the crash.