It's been nearly two years since Horst Stewin suffered life-altering injuries causing him to become an "aggressive and violent" man after being shot in the head as he and his family — visiting from Germany — drove along a highway west of Calgary.

The teen who pulled the trigger was handed a 21-month sentence Thursday by provincial court Judge George Gaschler. With the time he's already served, he will be released from custody right away.

"You need the support of your family," Gaschler said to the now-18-year-old from the Stoney Nakoda First Nation, who cannot be identified as he was only 16 years old at the time of the shooting, in August 2018.

"I encourage you to work together with an elder. I hope you are successful."

A sentencing hearing took place with prosecutor Dane Rolfe and defence lawyers Lisa Burgis Der and her husband, Balfour Der, presenting their arguments via teleconference before the judge, who accepted the joint submission between Crown and defence.

A victim impact statement written by Stewin's son paints a bleak picture of the changes the family has faced since the shooting.

Daniel Stewin says his father is no longer able to work and may lose his house.

Horst Stewin still has trouble speaking and being understood and has become "aggressive and violent toward his family," according to Daniel, who also says his father has considered suicide.

Last October, the teen was convicted of aggravated assault and recklessly discharging a firearm.

Youths convicted of crimes serve two-thirds of their sentence in custody and one-third in the community. The maximum sentence for the youth's convictions is 24 months.

The boy will now begin serving the seven month community supervision and 15-month probation portions of his sentence.

This is the gun police say was used to shoot Horst Stewin, who was driving on the highway west of Calgary in August 2018. The gun was buried in a wooded area by one of the people who had been in the vehicle with the shooter. (Court exhibit)

On Aug. 2, 2018, Stewin and his family — his wife, son and son's girlfriend — were in Alberta to celebrate his 60th birthday.

The family pulled off the highway onto Stoney Nakoda First Nation land near the Morley rodeo grounds, about 55 kilometres west of Calgary. Stewin stopped to take photos.

Ulrike Stewin told police her husband rides horses and was a fan of the western lifestyle.

Stewin then pulled back onto Highway 1A.

That's when a car carrying the teen and friends pulled up beside the German family.

These eight bullet fragments were removed from Horst Stewin's brain by German doctors three weeks after he was shot while driving west of Calgary. (Court Exhibit)

Stewin's son said there was a loud noise, which he first believed was one of the SUV's tires exploding.

Then his father's head slumped down.

The Stewins' rented SUV veered off the highway and crashed into a bank of trees.

The only hint as to a motive was a case of mistaken identity — the driver of the car carrying young people from the Morley community believed the person in the black SUV was a man who had attacked his brother.

Gaschler noted the boy "had fallen into a friendship with an adult male," which was "negative and destructive." The older man provided the teen with alcohol and meth.

One of the passengers in the car testified that the driver ordered the teen to shoot at the SUV driver.

Victim suffers lifelong injuries

During the trial, the judge heard evidence the boy confessed to the shooting to a friend in Facebook messages.

Other young people from Morley who were in the same car as the shooter testified the teen pulled the trigger.

One of three people in the car that day said they were all intoxicated on meth and vodka.

Stewin was taken to hospital and eventually flown back to Germany, where doctors removed eight bullet fragments from his brain.

"All of our lives changed," Daniel Stewin wrote of that day on the southern Alberta highway.

The family "still does not live a normal life."