Walter Liedtke, who served for 35 years as a curator of European paintings at the Metropolitan Museum of Art and was a renowned scholar on Vermeer and the Delft School, died on Tuesday, one of six victims of the crash of a Metro-North commuter train in Valhalla, N.Y. He was 69.

His death was confirmed by the Met’s director, Thomas P. Campbell, who said in an interview that “he was one of our most esteemed curators and one of the most distinguished scholars of Dutch and Flemish painting in the world.”

Mr. Liedtke, who lived in Bedford Hills, N.Y., and was raised in New Jersey, intended to be a teacher, and after earning his master’s degree at Brown and a doctorate at the Courtauld Institute of Art in London, he spent four years on the faculty at Ohio State. But in 1979 he received a Mellon Fellowship to study at the Metropolitan Museum, and he never left it.

The next year he became a curator and began producing a procession of well-regarded exhibitions and books over the decades, including “Rembrandt/Not Rembrandt in The Metropolitan Museum of Art” in 1995 and 1996; “Vermeer and the Delft School” in 2001, and “The Age of Rembrandt” in 2007.