The auction house that handled the sale of what has turned out to be a fake Gottfried Lindauer painting says there could be other fake Lindauers waiting to be uncovered.
The Alexander Turnbull Library paid $75,000 for what it thought was a 19th century portrait. However, the police are now investigating after the painting was revealed as a forgery.
Auctioneer Dunbar Sloane said his company was the agent when the painting was sold in April 2013, and that historical art works were assessed by experts.
Mr Sloane said the fact it was bought by the Turnbull Library was a ringing endorsement for the piece, as the library was often used to authenticate work.
But a recent analysis has shown the painting to be a fake - with the presence of titanium dioxide in the piece, which was not available as an artist's pigment when Lindauer was painting.
Mr Sloane said he had heard there was a forger at work about 40 years ago.
"There seems to have been a pattern involved where these paintings, I've heard through the grapevine, came from the Palmerston North area, the Hawke's Bay area, maybe in the 1970s to the mid-'70s," he said.
"Someone was faking them... They've slipped through the system but they've been slowly caught out over time."
Mr Sloane said this particular painting was brought in by a man who said he had bought it about 30 years before, as a Lindauer, from another auction house.
He was surprised at the recent news, but said "Goldies" (works by Charles Goldie) and Lindauers "attract the people who want to fake them, there's big money involved".