A reserved judgment released by Judge Phillip Cooper revealed new details of the police case.
Police allege that after the shooting, the defendant - then aged in his late 30s - travelled to Wellington and confessed to his estranged wife that he had killed Mr Tahu just a few hours earlier.
Since then, the defendant and his wife have divorced and changes to the Evidence Act in 2006 removed what was previously termed spousal immunity.
Under the old law, the Crown could not compel a spouse to give evidence without the consent of the husband or wife charged.
The law gave further protection to spouses in any court proceedings by protecting disclosures made duringa marriage by one partner to theother.
But the 2006 law change did away with that protection and led to Bay of Plenty police laying the murder charge in December.
"The police contend that the evidence of the confession is now available to them, along with other evidence which the informant says strengthens the prosecution case," Judge Cooper said in his ruling released yesterday.
The documents show the defendant wanted name suppression to continue for fear of the impact of media attention on his daughters and grandchildren.
But Judge Cooper said the man had been estranged from one of his daughters for more than 20 years and she now had a different surname.
He was also not persuaded that the family circumstances set out in affidavits outweighed the presumption in favour of open reporting and ruled that name suppression should be lifted.
Mr Temm appealed against that decision and legal arguments will now be heard in the High Court at Rotorua.
The man has still not entered a plea. He has been remanded on continued bail until February 10 when a post-committal conference will be held.
Mr Tahu was a father of two sons and a popular local who refereed children's Saturday rugby matches.
The 32-year-old Shell service station attendant was found by a passing truck driver lying in a pool of blood next to a petrol pump with gunshot wounds to his head and shoulder.
He was rushed to Taumarunui Hospital but died shortly afterwards.
It is thought to be the oldest cold case in New Zealand history to end in an arrest.