Police were called to the Eastern Tce property in Beckenham about 8.20am and found a man dead at the scene.
Police said on Sunday the circumstances of his death remained unclear, and they were "working to understand what occurred in the lead-up to this incident".
Detective Senior Sergeant Daniel Overend said they were particularly focused on tracing the man’s movements over the past two weeks, and were appealing to the public for any information that may assist.
On Monday, the New Zealand Herald reported a specialist search team scoured the property in a bid to determine what had happened and how the man had died.
The victim's Facebook page features posts showing specialist rifles, pistols and military models, the Herald reported.
A box with 'Crosman Air Guns' on it could be seen through the window of the man’s home, the Herald reported.
A Crosman-branded gun was one of the weapons the man had previously posted about online.
Police are appealing to the public for information and want to hear from anyone who may have seen or spoken with the man in recent weeks.
"We are committed to establishing the full circumstances surrounding this man’s death," Overend said.
"This is a perplexing case, and we are keeping an open mind as we work through a number of inquiries."
- If you have information that could help police, call 105 and use file number 251004/7850, or phone Crime Stoppers on 0800 555 111.
-RNZ and Allied Media
