It appears the building has been well-visited, with animal and human faeces, drug paraphernalia, spray cans and rubbish throughout.
The Derelict NZ member said he was about leave before he thought he would check one last corridor – that's when he came across the documents on the floor of the dusty offices.
"They had NZ Police on the front along with the emblem so I knew they were something which shouldn't be there," said 'Harley'.
"But after having a quick flick through one which was sitting on the chair I realised what they were. The person name, photo etc is all there inside for anyone who enters to look through."
He said he hasn't reported the find to police, as he was trespassing at the time.
"Although I'm only taking photos and documenting these places, I don't think they would see it like that," he said.
"Surely you would think they would have at least allowed qualified professionals in to remove such stuff though."
The building also housed other businesses, including orthodontists and yoga classes.
'Harley' said he also found "multiple rooms full with patient records" in the orthodontists, along with facial photos, X-rays, and cupboards full with "hundreds of dental moulds all named and dated".
"It's quite sad but also at the time quite amazing to walk into something which has just been left like this," he said.