THE HAGUE, Netherlands (AP) — Experts say a photo thought to be of a young Vincent van Gogh has turned out most likely to be of his brother, Theo.

The Van Gogh Museum in Amsterdam said Thursday that forensic testing by experts at Amsterdam University "confirmed the high likelihood of the boy in the photograph being the 15-year-old Theo van Gogh, and not Vincent."

The museum says there is now only one known photographic portrait of the camera-shy Dutch artist.

The photo was first publicly presented in 1957 by researcher Mark Edo Tralbaut. A Dutch television program called into question whether it was indeed of Vincent in 2014, prompting further research.

Museum Director Axel Rueger says the discovery "means that we have rid ourselves of an illusion, while gaining a portrait of Theo."