A 49-year-old Perth man convicted of murdering two people has been sentenced to life in prison with a 22 year minimum.

Gary Edmund Brown repeatedly stabbed Jenni Barrett, 29, and her partner Christopher Stoodley, 36, with a 20 centimetre blade at a flat in Maylands in 2011.

They victims also suffered head injuries after being attacked with a dumbbell.

Brown had pleaded not guilty to the charges, saying he was not of sound mind at the time as he was detoxing from methadone and suffering adverse effects from medication he was taking.

However, he was found guilty of the murder during a judge-alone trial in August.

Today, Justice Lindy Jenkins ruled Brown would have to serve at least 22 years in prison, describing it as a vicious unprovoked killing.

In sentencing, she took into account Brown’s mental state at the time but she did not accept it took away his control.

Jenni Barrett’s brother Adam was in court today and says he is relieved.

“Got what he deserved and hopefully he doesn’t come back out into society because he doesn’t deserve to be out here,” he said.

Mr Stoodley’s aunt Meg Smith says the double murder had a serious knock-on effect, especially for the couple’s 5-year-old son.

“The impact that it has on so many other lives,” she said.

“Especially the fact that Kyuss has been left an orphan.

“It’s amazing the domino effect that it has with an incident like that that has taken two wonderful people.”