Hope Mills, N.C. — The father of a driver who died in a head-on collision last week said Monday that his son's epilepsy might have led to the wreck, which also killed three other people.

Police said a Mustang driven by Tristan Hanna, 26, of Webster, N.Y., crossed the center line on Hope Mills Road on Thursday afternoon and hit an SUV carrying a family of three.

Hanna, the driver of the SUV, Hien Truong, 26, and Truong's 11-month-old daughter, Hanna, died in the wreck. Hanna's girlfriend, Brooke Paquin, 32, died Saturday at New Hanover Regional Medical Center in Wilmington of the injuries she suffered in the collision.

Truong's wife, Huyen Truong, 26, was released Monday from Cape Fear Valley Medical Center.

Police said Hanna was driving an estimated 65 mph in a 45-mph zone at the time of the wreck, police said.

"The facts surrounding the accident are not at all consistent with his personality and his driving," Brendan Hanna said of his son. "He was not reckless. He was not hot-headed. He was not an emotional driver."

Tristan Hanna completed a 13-week contract as a nurse at Cape Fear Valley Medical Center last week and was headed back to his home near Rochester, N.Y., at the time of the wreck, Brendan Hanna said. Paquin, who also was a nurse, had flown down to accompany him on the 700-mile trip, he said.

"It was a perfect combination of one person completing the other," Brendan Hanna said of the couple's relationship, noting his son was quiet and Paquin was lively.

Before heading to New York, though, the couple planned to spend the night at the Wrightsville Beach home of Tristan Hanna's great-aunt, his father said. He said his son planned to propose marriage to Paquin during the trip.

Brendan Hanna said his son was treated as a child for epilepsy, but that it was under control and he hadn't suffered a seizure in years. He said the excitement about the proposal might have triggered a reaction, leading to the wreck.

"I do know how he reacts when a seizure occurs. The stiffening of his body would be consistent with the accident,” he said.

Investigators likely will never know whether Tristan Hanna suffered a seizure because no autopsy was done, police said. A toxicology report on him will be complete in the next 60 days, police said.