Another of Mr Tahu's old friends Keith "Sarbie" Quinton said he last saw him shortly before he was gunned down.
Mr Tahu was an original member of the Turangi Rod and Custom Club.
The pair chatted about upcoming club business as Mr Tahu closed the pumps down at the service station.
"I think he had locked up at that stage and I was yakking with him and I probably left about 10 minutes before that guy drove in," said Mr Quinton.
Meanwhile, a legal expert says he is confused by police claims that changes to laws regarding the admissibility of evidence helped secure a breakthrough.
Police would not reveal to media the information that led to the arrest.
Auckland University Faculty of Law associate professor Scott Optican said he was confused by this. "What exact piece of evidence are you saying now has a greater claim of admissibility under the Evidence Act than it did prior to 2006?
"I'm not sure what the answer to that question is." Mr Optican assumed the police case was based mainly on forensic technology, which, he said, probably allowed them to test DNA samples from one of the crime scene packs.
Mr Tahu was 32 years old when he was gunned down on the morning of August 16, 1979, outside the Turangi Shell service station where he was an attendant.
The father of two suffered gunshot wounds to the head and shoulder and was rushed to Taumarunui Hospital but died of his injuries.
Yesterday the man accused of murdering Mr Tahu appeared surprised but relaxed when approached by the Herald at his central Rotorua home. He would not indicate how he would plead and said: "you'll have to wait and see".