The gunman who murdered a guard at the Washington D.C. Holocaust Museum Wednesday was a neo-Nazi, police revealed Thursday. The shooter, James W. von Brunn, began following white supremacist leaders in the 1970s.

In 1981, von Brunn broke into the Federal Reserve Bank's Washington headquarters, armed with guns and a knife, in an attempt to kidnap board members. He was arrested and sentenced to 11 years in prison, of which he served six.

Von Brunn repeatedly expressed hatred of Jews and African-Americans, and wrote documents urging white Americans to remove both groups from the United States. He also ran an anti-Semitic website and wrote a book accusing Jews of inventing the Holocaust and attempting to “destroy the white gene pool.” His racism was documented by the Southern Poverty Law Center, which kept tabs on his writings as early as the 1980s.

Von Brunn entered the Holocaust Museum on Wednesday and began shooting, killing private guard Stephen Johns, who managed to fire back before his death. Johns, 39, was African-American; it is not clear if he was targeted due to his race.

Two other guards fired on von Brunn, critically wounding him and putting an end to his attack.

The Holocaust Museum was closed Thursday in memory of Johns, and its flags were lowered to half-mast. Johns “died heroically in the line of duty,” said Museum Director Sara Bloomfield.

Israel issued a statement Thursday, saying the attack was “further proof that anti-Semitism and Holocaust denial have not passed from the world.”

Young Israel President Shlomo Mostofsky said Wednesday, “Today's horrific shooting serves as a sobering reminder that hatred and bigotry still exist in our neighborhoods and communities.” The gunman “single-handedly undermined the virtues and ideals that the memorial was established to promote,” he added.

Mostofsky sent condolences to relatives of the slain guard, and warned Young Israel synagogues not to ignore the need for security.

The Yad Vashem Holocaust Memorial in Israel sent condolences as well, and offered to assist staff at the Washington Museum.