The Dutch artist was able to paint many self-portraits during his 37-year life, one of which belongs to the museum's collections. But in the 1970s, questions were raised about the authenticity of the painting.
The reason for the speculation was the artwork's owner's history and, for van Gogh's, unusual painting technique and the use of colors.
In 2014, the National Museum signed an agreement with the van Gogh Museum in Amsterdam to let experts go to the bottom of the matter.
After several years of thorough investigation, it has now been established that the famous artist is in fact the author of the portrait. This is probably the first painting he painted after a period of illness in 1889.