The Corruption and Crime Commission is investigating allegations of misconduct by WA police over a murder conviction in 2009.

The allegations relate to the way police collected and handled the evidence that led to Scott Douglas Austic being sentenced to 25 years in jail for the wilful murder of Stacey Thorne, 35.

She died from multiple stab wounds at her Boddington home in 2007.

Austic pleaded not guilty to the murder and was unsuccessful in an appeal against the conviction.