A now-retired Whitehorse teacher who sexually assaulted a former student in the '80s will serve three years in prison.

Deputy territorial court judge Brian Neal sentenced Paul Deuling in a Whitehorse courtroom Tuesday morning.

The 73-year-old showed little reaction as Neal read his sentencing decision, and as deputy court sheriffs led him away immediately afterwards.

Deuling was found guilty of one count of historic sexual assault following a trial last year, but acquitted on three other sexual assault charges and one count of indecent assault on a female.

All five charges, which police laid in 2019, were related to the same victim, whom Deuling had taught, coached and mentored in elementary and junior high school. Her name is covered by a publication ban.

For the charge he was convicted on, Neal found that Deuling, in October 1986, had driven the victim to a remote location and had non-consensual sex with her twice. The victim was a 17-year-old high school student at the time.

In sentencing arguments last month, the Crown asked that Deuling receive four years of incarceration, while the defence said two-and-a-half to three years would be sufficient.

Community didn't know 'the other face of Mr. Deuling,' judge says

In his decision, Neal said the victim made it clear in a "powerful" victim impact statement that Deuling's actions had had a "profound and debilitating" effect on her, leaving her feeling "shamed and hated" by the community and straining her relationship with her family. It also opened her up to being preyed on by others, Neal noted, and she still lives with flashbacks and has difficulty trusting men more than 30 years later.

Neal cited the "devastating" and lasting impact of the crime as among the aggravating factors in the case. Other aggravating factors included the fact that the victim was a child, that Deuling was 20 years her senior and in a position of power, that Deuling had non-consensual intercourse with her twice in an isolated location he'd chosen, and that his actions represented a breach of trust.

Mitigating factors listed by Neal, meanwhile, included Deuling having an otherwise clean criminal record, Deuling's very low risk of reoffending and the fact that he was elderly with significant health issues.

Deuling, Neal noted, lost 22 pounds after being charged and had a medical emergency after being convicted which doctors attributed to stress.

But while Deuling was largely seen in a positive light — he received numerous letters of support that highlighted his contributions to the community, including teaching for more than 30 years and in retirement taking students on trips to Europe to learn about the Second World War —  what people didn't know was "the other face of Mr. Deuling," Neal said, and his actions needed to be denounced by the court.

Out of a possible sentencing range of two-and-a-half to four years, Neal said that under the circumstances, a three-year sentence would be fit.

Neal also ordered Deuling to provide a DNA sample to be entered into a national database, and for Deuling to be subject to the federal Sex Offender Information Registration Act for the next 20 years. Neal declined to make a weapons prohibition order and also waived the victim fine surcharge.

The victim has an ongoing lawsuit against Deuling which has yet to go the trial.