Police have searched two properties and examined two vehicles in their hunt for Ronny Okeke who was last seen 47 days ago.
Officers have also spoken to a person of interest as they build a picture of the movements of the 60-year-old Sandringham man for whom they hold "grave concerns".
"No arrests have been made at this point, but I can confirm we have since spoken with a person of interest in relation to Ronny's disappearance," Detective Inspector Glenn Baldwin of Auckland CIB said.
"We now have information that an altercation occurred between this man and Ronny on, or around, 27 April.
"It is believed Ronny may have been injured as a result, but as for the severity of any injuries we still do not know."
Detective Inspector Baldwin said two search warrants were conducted in late May, at addresses in Mt Eden and Ramarama.
Police have also examined two vehicles of interest. Forensic testing was being carried out on several samples and items.
Okeke was last seen on 27 April, leaving the New World supermarket in Mt Roskill, and police say his whereabouts since then have remained a mystery.
Police have not charged the man they interviewed and no other arrests have been made in connection with his disappearance.
"What we do know is that this altercation occurred, and Ronny has not been heard from since," Detective Inspector Baldwin said.
"The investigation team are continuing to keep an open mind around Ronny's disappearance but we undoubtedly have grave concerns for him at this point."
The investigation team have since recovered Okeke's mobile phone.
"This is an important piece in the puzzle and work is ongoing to interrogate the phone, and extract all possible relevant information," Baldwin said.
The New Zealand Herald is reporting Okeke was charged with two counts of money laundering in May 2021.
At the time police were targeting Ye "Cathay" Hua, who laundered millions for a transnational drug syndicate from her Newmarket money remittance business, Lidong Foreign Exchange in Kent St, the article says.
Hua was sentenced to seven and a half years in prison, the longest term handed down in New Zealand for money laundering.
However, the charges Okeke faced were dropped by the prosecution later in 2021, the Auckland District Court confirmed.
Meanwhile, police still want to hear from anyone who has information about the events of 27 April or who has seen Okeke.
"If you have information or if you have been involved in helping Ronny lay low, or seek medical attention, I urge you to come forward.
"Ronny's family are nearing two months without hearing from him, and being overseas they are understandably distressed and concerned for him."
Police can be contacted on 105 or going online, using 'Update My Report'. The file number is 240501/3879.