His name is Hans-Joachim Bohlmann, from Germany, also known as the 'acid assassin'. Between 1977 and 1988 he attacked 165 other paintings, causing damage for about E 130 million. He destroyed paintings by well-known artists, such as Rembrandt, Albrecht Dürer, Paul Klee and Lucas Granach.

He has been in prisons and psychiatric hospitals for over 20 years, from which he escaped various time, and was released some years ago, because he was not treatable any more.

The German wikipedia has a separate entry about the man.