(CNN)A simple act led to an art history professor discovering a 17th century masterpiece that was thought to have been missing.
Church of the Holy Family is located just a few blocks from the campus of Iona College, and Tom Ruggio told CNN he would sometimes visit during the church's "off hours" for the quiet and solitude.
Ruggio lived in Italy for about nine years studying art, and when he walked in the church with the lights a little brighter than normal, he couldn't believe what caught his eye.
"Up in the middle of the church, high up on the right side, I immediately identified an Italian Baroque painting, and I couldn't believe what I was looking at," Ruggio said.
"So, I got up and started taking pictures with my cell phone and I was very excited. I was initially stunned, but very excited."
Ruggio contacted colleagues in Italy and came to find out the painting was a piece by Cesare Dandini, called "Holy Family with the Infant St. John." The painting has been hanging in the church for the past 60 years, but Ruggio estimates it was painted in the 1630s, based on some other works of art.
The painting is part of a series of four works called "Charity." Another of the Dandini paintings hangs in the Metropolitan Museum of Art in New York, with a creation date around the same time, and a third is in the Hermitage in St. Petersburg, Russia. The fourth painting is unaccounted for. Ruggio said only a black and white photo proves its existence.
"The four paintings are connected and, fascinatingly enough to me, is doing something that most Baroque painters aren't doing any more in the 17th century. Many of them are going straight to canvas," Ruggio said. "So my contention is, he's part of a Renaissance legacy, and continuing the tradition of working on paper."
The paintings are also painted in a sort of cartoon style, Ruggio said.
"It's pretty fascinating. So, not only do we get a strong -- pretty much as I call a slam-dunk -- attribution because of the connecting paintings, but we also get a look at its process," he said.
So how did the painting end up in the church all this years? Well, that part is still a mystery, Ruggio said. It's rumored to have been bought abroad by one of the church's former monsignors in the 1960's, he said.
But now, the painting is being loaned to Iona for three months in an exhibit on campus. It's free for the public and includes reproductions of the corresponding works, and some works that explain Dandini's development and his process.