A fresh appeal for information on the cold case murder of a woman has raised the reward amount to $500,000.

Dianne Mary Angwin was 50-years-old when she was allegedly woken from her sleep at her unit on Leichhardt St in Bowen, 200km southeast of Townsville, about 12.30am on December 2, 1997.

An intruder or intruders had broken into the unit and stabbed her in the chest.

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She was rushed to the hospital where she later died.

A post mortem examination revealed the stab wound had severed her right carotid artery while she also suffered another “deep cut” to her right palm.

Angwin was last known to frequent multiple venues in Bowen and was last seen the night prior to the attack “socialising at the Bowen Bowls Club”, according to police.

Investigations into her murder have remained cold despite police announcing previous rewards of $250,000 in the years since.

Dianne Mary Angwin, 50, was stabbed to death in her unit in Bowen in December 1997. Credit: Queensland Police

Previous rewards have also featured an “appropriate indemnity from prosecution” being recommended for any accomplice in the murder.

Angwin was murdered just weeks after retired school teacher Herbert Murray was killed in his home.

Murray’s body was found at his home on the Pennsfield Station property, about 20km southwest of Angwin’s unit, on the morning of November 13, 1997.

He was found to have been shot once in the forehead by a .22 calibre firearm and his Holden Commodore stolen.

The car was dumped in Townsville soon after but police noticed it in March the following year.

A $250,000 reward is in place for information regarding his murder.

Anyone who can aid investigations into either cold case has been urged to contact Crime Stoppers.