The Wewak National Court handed down the court decision to French William, of Western Highlands, on Thursday 18th April.
First Constable William was arrested in 2014 for his alleged involvement in the murder of one Othoniel Kapris.
Investigations revealed that the male victim was beaten to death while being detained at the Maprik Police Station Cell block 1.
William had reportedly picked up Kapris and a group of others on the 14th August of 2014, when he responded to a commotion at the Top Hill area of Maprik Town.
He transported the group to the police station lock up.
Hours later Kapris was found dead inside the cell with visible wounds and bruises on his body.
First Constable William and another officer were arrested and charged with wilful murder.
With a not-guilty verdict, First Constable William, who has made a home in Maprik for more than eight years, will continue his duties as a police officer in the district, despite the public animosity after his arrest.