How does a home-grown terrorist like Frazier Glenn Cross Jr. end up in the back of a police car shouting "Heil Hitler" after he has killed three people and shot up two Jewish community facilities in suburban Kansas City?

Does he start with an ideological gateway drug, like a stream of shrill propaganda from the NRA? Does he move on through progressively harder stuff, from the pompous rants of Rush Limbaugh, to the paranoid fantasies of Glenn Beck and then to the seditious lunacy of Alex Jones? Does this get him hooked on anti-government delusions that take him deep into the philosophical meth, heroin and crack of right-wing extremist websites and white supremacist militia groups?

Or do men like Mr. Cross just start crazy and get crazier?

Whatever the case may be, the shooting in Kansas City is another reminder that we continue to have a domestic terror problem. While the vast power of the U.S. military and intelligence agencies is targeted on radical Islamists around the world, we, as a country, show minimal concern about the threat of militants who have grown up among us.

The 73-year-old Mr. Cross spent four decades pushing the white supremacist cause. Mr. Cross served as grand dragon of the Carolina Knights of the Ku Klux Klan. He threatened to assassinate the founder of the anti-racist Southern Poverty Law Center. He spent time in prison, but also ran for political office several times on a white power platform.

Tuesday night on MSNBC in a report on Mr. Cross' connections to the broader extremist movement, Rachel Maddow cited the bizarre fact that Cross -- then known by the last name Miller -- was a key FBI informant in an unsuccessful federal effort in the 1980s to bring down the major players in the white supremacist movement. Despite his betrayal, Mr. Cross returned to the cause and cheered on other racist militants, such as Kevin Harpham, the man convicted of placing a bomb along the route of Spokane's Martin Luther King Day parade in 2011.

When he went gunning for Jews last weekend, this guy did not spring out of nowhere. He was notorious. So, why was he off the radar of law enforcement?

In 2009, when federal agencies wanted to step up monitoring of extreme right wing groups, many conservatives went ballistic. They said the feds would use this as an excuse to go after anti-abortion activists and other legitimate political organizations on the right. They succeeded in getting law enforcement to back down.

They may also have succeeded in making the homicidal work of a domestic terrorist that much easier.

Two-time Pulitzer Prize winner David Horsey is a political commentator for the Los Angeles Times. Go tolatimes.com/news/politics/topoftheticket/ to see more of his work.