A painting acquired at a Minnesota garage sale for less than $50 has been identified as a previously unknown work by Vincent van Gogh, according to a detailed analysis by experts commissioned by the art research firm LMI Group International. The portrait, depicting a bearded fisherman repairing his net while smoking a pipe, is believed to have been painted during Van Gogh’s stay at a psychiatric hospital in southern France in 1889.

The discovery was made after a four-year authentication process that examined the canvas weave, paint pigments, and other technical details. Researchers also found a human hair embedded in the paint, though DNA analysis was inconclusive due to its degraded state. The painting, measuring 45.7 by 41.9 centimeters, bears the inscription “Elimar” in the bottom right corner and is based on a work by Danish artist Michael Ancher.

Van Gogh often created “translations” of other artists’ works, and this piece is thought to be one such example. Despite the thorough analysis, the Van Gogh Museum in Amsterdam has yet to officially attribute the painting to the Dutch master. The museum previously declined to authenticate the work when approached by its former owner in 2018.

LMI Group, which acquired the painting in 2019, remains confident in its findings. “The discovery of a previously unknown van Gogh painting should come as no surprise,” the firm stated, noting that Van Gogh frequently gave away or lost works, especially those he considered studies.

The painting is described as an “emotionally rich, profoundly personal work” created during a tumultuous period in Van Gogh’s life. The artist, who suffered from mental health issues, produced around 900 paintings before his death by suicide in 1890 at the age of 37.

The anonymous antiques collector who purchased the painting in 2016 has yet to be identified. If authenticated by the Van Gogh Museum, the work could be worth an estimated $15 million.