OVERLAND PARK, Kan. (AP) — Never one to keep his hatred to himself, Frazier Glenn Cross for decades sought out any soapbox to espouse his white-supremacist beliefs, twice running for federal office with campaigns steeped in anti-Semitism.

Yet there’s scant evidence the Army veteran and retired trucker with Ku Klux Klan links ever resorted to violence before Sunday, when authorities say he opened fire with a shotgun and pistol outside a Jewish community center and retirement complex near Kansas City. None of the three people killed turned out to be Jewish.

The 73-year-old Cross, who shouted a Nazi slogan at television cameras when arrested minutes later, has been jailed awaiting charges that investigators said could come as early as Tuesday. At some point, a federal grand jury is expected to review the slayings, which authorities now deem a hate crime.

U.S. Attorney Barry Grissom said the victims “happened to be in the wrong place at the wrong time” and had “a firsthand encounter with evil.”

The FBI and police have not offered any public explanation for what triggered Sunday’s deadly outburst in Overland Park on the eve of the Jewish festival of Passover. While the FBI and other law-enforcement agencies were familiar with Cross, Sunday’s gunfire was “very random,” the FBI’s Michael Kaste said.

“We don’t really see how this could have been prevented. There’s at least no obvious answer,” said Mark Potok, a senior fellow at the Alabama-based Southern Poverty Law Center, which tracks hate groups and had a considerable dossier on Cross. “He is one of the more frightening characters out there, no question about that.”

A Johnson County jail official reached Monday by The Associated Press refused to make Cross available and referred inquiries to his attorneys and Overland Park police. The Kansas City Star reported that Cross had been assigned two federal public defenders.

Knocks by an Associated Press reporter went unanswered Monday at Cross’ small, single-story home bordered on three sides with barbed-wire fences near the southwest Missouri town of Aurora, some 180 miles south of Overland Park. Parked outside was a red Chevrolet bearing two Confederate flag stickers.

In nearby Marionville, Mayor Dan Clevenger said Cross often distributed racist pamphlets.

The Southern Poverty Law Center said Cross, who also went by the name Frazier Glenn Miller, has been immersed in white supremacy most of his life. During the early 1980s, Cross was “one of the more notorious white supremacists in the U.S.,” according to the Anti-Defamation League.

He founded the Carolina Knights of the Ku Klux Klan and served as its “grand dragon” before launching the supremacist White Patriot Party, the law center said.

By 1987, he was the target of a nationwide manhunt for violating terms of his bond while appealing a North Carolina conviction for operating a paramilitary camp. Federal agents tracked him along with three other men to a rural Missouri mobile home stocked with hand grenades, automatic weapons and thousands of bullets.

A federal grand jury indicted Cross on weapons charges and accused him of plotting robberies and the assassination of the law center’s founder, Morris Dees. He then served three years in federal prison. As part of a plea bargain, he testified against other Klan leaders in a 1988 sedition trial.

Cross-ran for the U.S. House in 2006 and the U.S. Senate in 2010, each time espousing a white-power platform.

During his Senate run as a registered write-in candidate, Cross’ effort to air anti-Semitic ads was scuttled by the Federal Communications Commission, which concluded Cross was not a “bona fide” candidate entitled to mandatory access to the state’s airwaves. The ruling allowed Missouri broadcasters to reject his ads, such as one that urged white people to “unite” and “take our country back.” It also criticized immigrants and minorities.

Violence proved fatal to his son. Jesse Miller was 30 and wielding a shotgun in 2008 when he was shot and killed by a police officer he wounded in Marionville. The confrontation happened moments after the younger Miller had gunned down a passer-by who stopped to help him after a car crash. It was never clear why Miller resorted to gunfire.

In Cross’ hometown Monday, most locals approached by the AP waved off the opportunity to discuss him.

He’s suspected of killing 69-year-old William Lewis Corporon, a physician, and his 14-year-old grandson, Reat Griffin Underwood, outside the Jewish Community Center of Greater Kansas City. Both were Methodist.

Moments later, Terri LaManno — a 53-year-old Catholic occupational therapist and mother of two — was gunned down outside a Jewish retirement complex where she was visiting her mother.

“It was bound to happen,” said Steven Roberts, who lives in Aurora. “You can’t be that deep into what he was into and not expect something to happen.”

– Jim Suhr & Maria Sudekum, Associated Press