Frazier Glenn Cross, 73, is accused of killing three people in attacks Sunday at a Jewish community center and Jewish retirement complex near Kansas City.

OVERLAND PARK, Kan. — A group monitoring anti-Semitic attacks in the U.S. cautiously noted a sharp decline in such incidents less than two weeks before the fatal shootings over the weekend outside two Jewish sites in suburban Kansas City.

The contrast between the Anti-Defamation League’s 2013 audit and the Sunday attack that killed three people highlights what hate-group trackers say is a broader trend: more overall tolerance disrupted by periodic bursts of violence from a disenfranchised fringe.

“Because of their ability to strike fear in the entire Jewish community and the country, their impact is disproportionate to their occurrence,” said Mark Pitcavage, the ADL’s investigative research director. “Like any terrorist incident, they have the power to strike beyond the immediate victim.”

An avowed white supremacist is accused in the attacks outside the Jewish Community Center of Greater Kansas City and a nearby Jewish retirement home in Overland Park, Kan. The suspect, Frazier Glenn Cross, is a 73-year-old Vietnam War veteran from southwest Missouri who founded the Carolina Knights of the Ku Klux Klan in his native North Carolina and later the White Patriot Party.

Cross remained jailed today. It was unclear when formal charges would be filed against Cross, who shouted “Heil Hitler” at television cameras as he was arrested.

None of Sunday’s victims was Jewish. Dr. William Lewis Corporon, 69, and his grandson Reat Griffin Underwood, 14, were at the community center for a singing contest audition, while 53-year-old Terri LaManno was visiting her mother at the retirement complex.

After a 1986 contempt-of-court conviction in North Carolina for operating a paramilitary camp, Cross went in hiding while free on bond and fled to Missouri. There, federal agents found him and several other men in a mobile home stocked with grenades, automatic weapons and thousands of bullets.

Indicted on weapons charges and accused of plotting robberies and the assassination of SPLC founder Morris Dees, Cross served three years in federal prison but avoided a longer sentence in exchange for testifying against more than a dozen other KKK leaders.