For lone wolves, these guys sure have a lot of company.

On April 4, white-power conspiracy enthusiast Richard Poplawski laid in wait for police to answer his mother's call to get him out of their Stanton Heights house. When they arrived, he shot Officers Paul J. Sciullo II, Eric Kelly and Stephen Mayhle to death in cold blood.

On May 31, anti-abortion fanatic Scott Roeder tracked down abortion provider Dr. George Tiller on a Sunday morning at his church in Wichita, Kan., entered the house of prayer and killed him with a single shot to the head. Roeder had picketed Dr. Tiller's clinic in the past and knew he often wore a bullet-proof vest.

On June 1, Muslim convert Abdulhakim Muhammad fatally shot an American solider outside a military recruiting center. He later said that killing 23-year-old William Andrew Long wasn't murder because U.S. military involvement in the Middle East justified his actions.

And on June 10, an 88-year-old racist and anti-Semite with a name right out of a movie script entered the U.S. Holocaust Memorial Museum in Washington, D.C. with a rifle. James Wenneker von Brunn has been charged with murdering security guard Stephen Tyrone Johns, who had opened the door to help him.

Six killings in 66 days fueled by the doctrine of the lunatic fringe, four committed by rabid right-wingers, one by a religious zealot and one by a guy who fit both categories. All the shooters are said to have acted alone.

But of course they weren't really alone -- not in the social, psychological and ideological sense. They had a World-Wide Web teeming with like-minded compatriots feeding their paranoia, egging them on with crackpot theories, baseless slander, twisted theology and wild-eyed hatred.

They also had plenty of indirect support in more "mainstream" circles, from talk show headache Bill O'Reilly, who repeatedly likened Dr. Tiller to a Nazi, and other conservative pundits who denounced and ridiculed a recent Department of Homeland Security report warning of an increased domestic threat from right-wing groups.

Nor can we overlook the baseless fear-mongering by various talking heads on hot-button issues, guns in particular. Or the bizarre rhetoric of the Rev. Jeremiah Wright, the Chicago pastor Barack Obama severed ties with after his infamous "God-damn America" sermon went viral. On the same day as the Holocaust museum attack, an audio tape emerged of Rev. Wright accusing "them Jews" of keeping him away from the president (like he's not already radioactive enough), then sought to smooth things over by blaming "Zionists" instead.

It's doubtful that the racist von Brunn would have been influenced by a black preacher even if he had heard him, but it goes to the point that toxic words are not limited to the netherworld of cyberspace. Increasingly, they are filtering into public discourse that no longer seems to demand any responsibility.

And so, Newt Gingrich calls Supreme Court nominee Sonia Sotomayor "racist," then takes it back after the damage is done. Barack Obama is called a "left-wing Socialist" during the campaign, a label the voters rejected but some conservatives still cling to. Doctors providing safe, legal abortions are called "baby killers," their faces, names and home addresses widely distributed among the faithful.

Add hard economic times, which always exacerbate people's problems and expose the underbelly of "civilized" society, and here we are. Let's survey some of the damage.

Five of the victims were random. The three police officers from Zone 5 happened to answer the call to Stanton Heights that morning, just as the soldier happened to be outside the recruiting station and the security guard happened to be inside the museum door.

All of them were doing their duty when they died; none was known personally by his executioner. It was their extreme misfortune, and ours, that they wound up in the cross hairs of a fanatic's gun sight. All of them have left deep holes in their families and communities that will never be filled.

The sixth killing was an outright assassination. Dr. Tiller was specifically hunted by a stalker bent on taking him out, and the shooter was not the first one to have tried. Dr. Tiller's clinic was targeted for years by hordes of protesters. It was also bombed, and he was threatened repeatedly and shot in both arms. Nor was he the first abortion doctor to have been killed by a so-called "pro-lifer" -- Dr. Bernard Slepian was shot to death through his kitchen window by another religious militant in 1998.

Yet Dr. Tiller refused to be intimidated into closing one of only three clinics in the country where women could come for help in ending badly troubled, late-term pregnancies. He could have saved his own life by quitting, but considered it his duty to help patients who had nowhere else to go.

Most conservative Christians denounced Mr. Tiller's murder. But fearing a backlash, they also went on the offensive, warning abortion-rights groups not to make his death "political" -- as if abortion wasn't already among the most highly politicized issues in American life.

These shooters may not have known each other and may not have enlisted accomplices or directly conspired with anyone else in their crimes. If that's supposed to make us feel less threatened, it's not working. A forest full of lone wolves is still a very dangerous place.