The mother of a teenager killed by a dangerous driver is disappointed the man who caused her daughter's death has once again failed to act on his commitment to stop using drugs. 

Olivia Keightley-Trigg, 18, was killed by Kevin Ronald Bishell, 41, in a head-on crash in August 2018. 

In a remarkable show of compassion, the Taranaki teen's mother, Suzie Keightley, has since been offering him encouragement to turn his life around. 

Bishell promised the family he would kick his drug habit and leave behind his life of crime. 

But last month, less than four months after he was released from jail for causing Olivia's death, he breached a release condition by testing positive for amphetamine, methamphetamine and cannabis, court documents released to the Herald this week detailed. 

"We're disappointed he continues to choose that for his lifestyle," Suzie said, surprised to learn of his recent offending. 

"Our hope has always been that he would change." 

After the breach, Bishell appeared in New Plymouth District Court where he was sentenced to 12 months' intensive supervision. 

Olivia Keightley-Trigg, 18, was killed in a head-on crash in August 2018. 

The sentencing notes, also released to the Herald this week, stated Judge Chris Sygrove reminded Bishell he was not to consume non-prescription drugs and issued him with a warning. 

"If you fall off the rails, Mr Bishell, you will be back in jail," Judge Sygrove told him. 

Kevin Bishell was jailed for causing the death of Olivia Keightley-Trigg. Photo / RNZ 

Bishell was jailed in November 2019 for two years and six months after pleading guilty to dangerous driving causing death and refusing a request for a blood sample. 

On the day of the fatal crash, the ute he was driving crossed the centre line on State Highway 3 just south of Waitara and collided with the vehicle Olivia was driving. 

She died at the scene. 

Suzie was travelling in a vehicle ahead and watched her daughter's car disappear off the road in the rear vision mirror. 

After Olivia's death, Suzie and her husband, Olivia's father, Shaun Keightley, expressed hope that Bishell, who has an extensive criminal history and was on parole at the time of the crash, would spend his time in jail engaging in programmes to help better himself. 

And at a restorative justice meeting between the Keightleys and Bishell, he committed to doing just that. 

But while in prison, he twice appeared before the New Zealand Parole Board and was declined an early release as he was considered an undue risk. 

Olivia Keightley-Trigg with her parents, Suzie and Shaun Keightley. Photo / Supplied 

The board noted Bishell had failed in his commitment to Olivia's family to complete alcohol and drug treatment in prison. 

He was released on his sentence end date in September last year but was subject to standard and special release conditions for a further six months. 

While he was in prison, Suzie said they had written letters to one another. 

She described the content as "difficult and honest communication". 

Suzie also advocated for one-on-one treatment for his alcohol and drug issues, which the restorative justice process helped facilitate. 

"But he didn't take the opportunity." 

The family is disappointed by his lack of effort to rehabilitate, she said. 

But Suzie hasn't lost hope or compassion for Bishell. 

"My hope for him is to find contentment and inner peace, love and joy," she said. 

"That's what I've got, through my faith, and I want him to have that too." 

- by Tara Shaskey, Open Justice