She believed the painting was "homesick" and should be returned to New Zealand.
"It doesn't belong in North Carolina here among the pine trees and Republicans."
Ms McLean lived in New Zealand when she was younger, including in Whakatane and the Wellington region.
She bought the painting about nine years ago from an antique store in Petone.
Dr Duncan was born in Christchurch in 1881 and later moved to Rotorua, working for the health department.
He had no formal training as an artist and also spent time in Sydney and Europe.
A few days ago, the Rotorua Daily Post received a call from Katikati woman Gail Gresham-Cook who is the daughter of Dr Duncan's daughter Margaret King Duncan.
Mrs Gresham-Cook, now in her late 70s, said her sister told her the painting was of Crater Lake, between lakes Okareka and Tarawera.
Dr Duncan won the Bledisloe Medal for landscape of the year in 1934 and painted other works depicting the Rotorua landscape.
His paintings were also exhibited in the Auckland Art Gallery and Sarjeant Gallery in Whanganui.
"Grandfather did a lot of painting, mostly landscapes, and we are very interested in talking to this lady about having it returned.
"It is quite exciting really. I was reading about it and I was amazed.
"It would be wonderful to see it back, but we can't afford a lot so we need to speak to her.
"We used to visit my grandparents when they lived on Marine Parade at the Mount.
"He was a doctor and was very professional as I remember him, but he did have a quirky sense of humour as well."
The Rotorua Daily Post has helped connect Mrs Gresham-Cook and Ms McLean and is awaiting the result.