A DRUGGED woman who hit and killed a cyclist has been jailed for at least three years after failing to convince a judge to spare her prison so she could look after her child.

Samantha Magdaleine Farrer, 40, was found guilty of an aggravated charge of causing death by dangerous driving and leaving the scene of an accident after hitting cyclist Kathleen Heraghty on December 27, 2013.

On Friday, Judge Gordon Barrett imposed a five-year jail sentence with a non-parole period of three years, two months and 12 days on Farrer.

He refused to suspend her sentence or place her on home detention due to the seriousness of her offences.

But he did accept psychologist Luke Broomhall’s opinion that separating her and her child would have the potential to cause psychological damage to the 15-month-old boy.

“I do accept that separation from you, may have detrimental effects on him,” he said during his sentencing.

“In South Australia, offenders are not able to look after their children in prison.

“Mr Broomhall concluded that you had created a good home environment for your son and you had established a secure attachment to him.

“He concluded that separation from you would inevitably disrupt and damage the secure attachment and lead to negative consequences for the child.

“The negative consequences include psychological and psychosocial difficulties.”

media_camera Victim Kathleen Heraghty, 48, was killed when hit by Samantha Farrer. Picture: Supplied by family.

But Judge Barrett said the offending was “serious”, especially given Farrer left the scene of the accident.

“You have shown an incomplete acknowledgment of responsibility for your offending,” he said.

“In my view, the serious mitigating factors to which I have referred, do not outweigh the counter consideration. I do not find good reason to suspend the sentence.”

He said Farrer was a suitable candidate for home detention — a penalty which sits between a suspended sentence and custodial sentence.

“(But) in my view, it is not appropriate to suspend the sentence and order you to serve it on home detention,” he said.

“I find the seriousness of the offences, and general and personal deterrence, outweigh even the considerable weight that I give to the effective imprisonment on your son.

“I order that you serve the sentence.”

He also disqualified her from driving for 10 years.

Farrer, the former partner of Adelaide siege gunman Rodney Clavell, drove away after hitting Ms Heraghty on her bicycle as she trained for a triathlon on Iman Valley Rd, near Victor Harbor.

Judge Barrett said it was impossible for Farrer not to realise she had hit a person.

“Ms Heraghty’s body was flung by the force of the collision against the left-hand windscreen of the car you were driving,” he said.

“I found it would have been obvious to you that you collided with someone.

“You kept driving.”

media_camera Damaged sustained to nurse Kathleen Heraghty’s bike after being hit by Samantha Magdaleine Farrer. Picture: SA Police, released by District Court

Farrer later told police she thought she had a crashed into a sign for a roadside fruit stall.

Her lawyer, Gilbert Aitken, had asked for Farrer to be given a suspended jail term so she could care for her son.

In August, Ms Heraghty’s chronically ill mother, Mary, brother Patrick and sister Eileen each tendered moving victim impact statements to the court, in which they described their never-ending grief and urged an “appropriate” jail term.

Mr Heraghty, who had travelled from Glasgow to Adelaide for the trial, said their “life has been ripped apart” and had been “forever tainted by her absence”.

“We are unable to enjoy (any) future that is now drenched in pain at the lost opportunities,” he said as he told how his final words with his sister came a few days before she died in text messages as they celebrated Christmas.

Her sick mother, whom she visited multiple times with her children, spoke of her trauma at her daughter being taken “cruelly away”, leaving three grandchildren without a parent.

In an audio recording played to the court, she said: “Now she is in a cold, cold grave and I am not able to visit to see her or to pray over. Why, why, why. I have asked is this happening?”