A former couple who killed a convicted drug dealer after luring him to a house is due to be sentenced in the West Australian Supreme Court.

A jury acquitted Paulo Nunzio Stagno and Danielle Kovac of murder in March, but found them guilty of manslaughter over the shooting death of Mite Naumovski in September 2011.

The pair lured the 38-year-old to a Nollamara house following a dispute over a drug debt.

They claimed Stagno acted in self-defence when he shot Mr Naumovski in the head.

Mr Naumovski's body was found with six gunshot wounds in the back of a car less than two weeks after he disappeared.