The man convicted of murdering his 12-year-old girlfriend's family has been sentenced to life in prison.

Jeremy Steinke, 25, has been sentenced to life in prison with no chance of parole for at least 25 years.

Last week Steinke was convicted of three counts of first degree murder and on Monday more than 70 people filled a Medicine Hat courthouse for his sentencing.

Steinke's family members wept as Justice Adele Kent told him he would serve a life sentence for the horrific crime.

The mayor of Medicine Hat hopes residents can move forward and help put an end to a dark chapter in the city's history.

"I hope we can turn the page because there (are) so many nice things about Medicine Hat and the residents that we want to celebrate," said Mayor Norm Boucher.

The crown prosecutor read four victim impact statements in court from family members who could not be at the hearing in person. However, the brother of the murdered woman chose to read his statement in person, forgiving Steinke.

He said he will never understand the workings of "sick and twisted" minds, but he does understand forgiveness.

The bodies of Steinke's girlfriend's parents and 8-year-old brother were found in their Medicine Hat home in April of 2006.

The trial was held in Calgary, but due to the media attention, Crown Prosecutor Ramona Robbins, asked to have Steinke's sentencing moved back to Medicine Hat where the murders were committed.

Steinke's co-accused is now 15 and cannot be identified under the Youth Criminal Justice Act. She was found guilty of three counts of first degree murder in 2007.

She is the youngest person in Canada to ever be convicted of multiple homicides. She is serving the maximum 10-year sentence in a forensic psychiatric hospital.

With files from CTV Calgary