Nerida Greenfield told District Court Judge John Hatzistergos she would never forget seeing her husband Tony being thrown like a rag doll after being struck by retired police inspector Ken Grant.

Mrs Greenfield said she had to wait for more than two years for Grant to stand trial over the fatal hit and run and hear his "miraculous diagnosis" that he was sleepwalking.

"In the end, there wasn't one (an explanation of his actions). He was just drunk," Mrs Greenfield said, reading her victim impact statement at home to the court in Wollongong on Friday.

"It's difficult to describe the rage I was feeling after this."

Mrs Greenfield said the refusal by Grant to accept responsibility for the crash had weighed heavily on her, the couple's two children and the scientist's many friends and colleagues.

She said Troy Grant's claims after the fatal accident that his father wanted to trade his life for Mr Greenfield's was "all just spin".

Judge Hatzistergos found in November there was no reasonable possibility Ken Grant, 72, had been suffering from somnambulism when he crashed into Mr Greenfield.

Grant claimed he was either sleepwalking or had transient global amnesia (TGA), a sudden temporary episode of memory loss, or had sleep apnoea and was not driving voluntarily before the crash.

The key witness in the judge-alone trial, sleep and respiratory physician Anup Desai, said there was no evidence Grant had fallen asleep at a Christmas party before driving his ute erratically on two blown tyres and he did not believe he was sleepwalking before the crash.

Grant was found guilty of dangerous driving causing death, failing to stop after a fatal crash, being involved in a police pursuit and drink driving after running into Mr Greenfield at about 11.24pm on November 30, 2019, in Maitland.

The 62-year-old scientist died of his injuries at Newcastle's John Hunter Hospital.

Party guests described Grant as being "hammered" and "well and truly gone" before getting behind the wheel.

Grant, who returned a blood alcohol level of 0.108 after his arrest and had a later reading of 0.194 from blood tests, claimed to have no memory of the crash which threw Mr Greenfield 20m forward past his wife when they were walking to their accommodation after being at the party.

When Grant was pulled over by police and had to be dragged out of his car and handcuffed, he repeatedly told officers he was Police Minister Troy Grant's father.

At one stage he told police, "My son is Troy Grant, the police minister, and I'm pissed."

The judge accepted Troy Grant's evidence during the trial that both his father and his family had a history of sleep walking but the extent of that somnambulism in Ken Grant's later years was in dispute.

Troy Grant, who admitted his nickname was Goldilocks because of his own sleepwalking experiences, told the court on Friday his father suffered from entrenched post-traumatic stress disorder caused by his many years as a police officer.

He said his father had been confused and unable to reconcile what he had done after the fatal crash.

Mr Grant said his father was remorseful and had constant self-loathing but claimed his life changed forever in 1977 when he was kidnapped and tortured by four escaped prisoners accused of murder.

He said the family became dysfunctional after his father began to drink heavily following the kidnapping, but he believed there was little risk he would ever re-offend.

Crown prosecutor Lee Carr SC told the court Grant had to be jailed for more than three years because of his "gross abandonment of responsibility".

"The fact he has PTSD isn't in any way connected to the commission of this offence," the prosecutor said.

Grant, who remains on bail, will be sentenced on March 4.

Australian Associated Press