A drug-fuelled teenager who killed a couple and their unborn son when he ploughed into them in a stolen four-wheel drive will be released from custody six years to the day after the tragedy.

Matthew Field and partner Kate Leadbetter, who was six months’ pregnant, were walking their dogs south-east of Brisbane on Australia Day last year when the vehicle struck them.

The driver, who cannot be named because he was 17 at the time, ran a red light at Alexandra Hills in the LandCruiser, colliding with a truck before rolling and hitting the couple.

Mr Field, 37, Ms Leadbetter, 31, and their unborn baby – who was to be named Miles – died at the scene.

The teen fled, stealing keys from a nearby house before being caught by a resident and arrested.

Tragedy an ‘almost inevitable consequence’

Justice Martin Burns said the tragedy was as an “almost inevitable consequence” of the teen’s actions in the lead-up to the crash.

The teenager – who was first charged with murder, but pleaded guilty to two counts of manslaughter and a raft of other charges – stood stony-faced as he was sentenced.

Justice Burns said taking into account the teen’s protracted period of extremely dangerous driving that culminated in a grossly negligent final act, he regarded the manslaughter offences as “particularly heinous”.

But the teenager had to be sentenced as a child, with the “grave nature of offending” balanced by his youth.

Drinking and using cannabis on day of crash

The sentence was also based on the teenager not intending to kill or do grievous bodily harm.

“No sentence will be adequate … [and] can’t do justice to the suffering you have caused,” Justice Burns told the teenager.

The teen was found to have had a blood alcohol content between 0.151 and 0.192 per cent at the time of the crash.

He had been drinking and using cannabis from about 10am that day.

He went with a friend to Cleveland to get more cannabis, but the men separated after an argument.

He stole the LandCruiser 20 minutes before the fatal collision, driving “dangerously for a sustained period at extreme speeds” with no regard for anyone’s safety, Justice Burns said.

Teen drove at twice the speed limit

The teen, who had a learner’s permit, drove sometimes at twice the speed limit, on the wrong side of the road, doing a burnout on soccer fields, hitting one vehicle and nearly crashing on numerous occasions.

Justice Burns said the boy was travelling at 102km/h five seconds before the crash, with his brake lights seen to illuminate just before the collision.

The teenager’s upbringing was “marked by significant deprivation and neglect”, Justice Burns said.

The child safety department intervened when he was aged nine because he was self-harming, left unsupervised, unfed, and exposed to domestic violence and abuse.

At times he used cannabis and meth every day, was frequently absent from school, sometimes living in parks.

Justice Burns sentenced the teen to 10 years in detention, requiring him to serve 60 per cent. He will be released on Australia Day 2027 at the age of 23.

-AAP