A Perth man has been sentenced to life imprisonment for the second time over the brutal murder of another man in an Orange Grove caravan park four years ago.

Ryan Christopher Hawke, 37, stabbed and killed Mark Koller in April 2014 after he found out his partner had engaged in a threesome with the victim.

Hawke, who was a FIFO worker at the time, and Mr Koller lived at the same caravan park with their respective partners.

Mr Koller's brother, Mike, and his niece Rebecca outside Perth's Supreme Court on Monday. Credit:Kate Hedley.

On the night Mr Koller was killed, Hawke had confronted him with a knife.