Vincent van Gogh probably committed suicide because he was despondent that his brother suffered from terminal syphilis, a University of Pittsburgh professor said Monday.

Art history professor Aaron Sheon, a recognized Van Gogh expert, said he has examined century-old medical records found in the Municipal Archives in Utrecht, the Netherlands. The records indicate Theo van Gogh suffered from tertiary syphilis, not kidney disease as earlier believed.In an upcoming article in the Van Gogh 100 Anthology published by Hofstra University, Sheon contends the artist committed suicide because Theo was dying of syphilis and would no longer be able to support him.

Van Gogh shot himself to death on July 29, 1890.

Van Gogh never explained in his suicide letter why he took his life and the just-discovered records are "the closest thing we have to a smoking gun," Sheon told the Chicago Sun-Times.