Police have launched a homicide investigation after a man was pulled dead from the Waikato River in Ngāruawāhia on Thursday night.

He has been named as 52-year-old John Wirihana Isaac, of Hamilton.

His body was discovered at about 7pm on Thursday, January 18 by members of the public who had taken their boat to the river.

Detective Senior Sergeant Ross Patterson said a post-mortem examination has led to police launching a homicide investigation.

“To protect the investigation at this early stage, police are not in a position to elaborate on the cause of Mr Isaac’s death,” Patterson said.

Police were, however, asking to hear from anyone who had seen Isaac in the past few days or who had noticed any unusual activity near the river and any of the bridges between Hamilton and Ngaruawahia.

Anyone with information is asked to call 105, or make a report anonymously to CrimeStoppers by calling 0800 555 111.

“This is an incredibly distressing event for Mr Isaac’s whānau, and we are providing them with support at this time.”