WICHITA, Kan. - Scott Roeder harbored a burning, "eye-for-an-eye" anger toward abortion doctors. He once subscribed to a magazine suggesting "justifiable homicide" against them, and apparently likened Dr. George Tiller to the Nazi death-camp doctor Josef Mengele.

Roeder, 51, was in jail yesterday on suspicion of murder, accused of shooting Tiller to death Sunday as the doctor served as an usher at his Lutheran church in Wichita.

Police said it appeared the gunman acted alone, and some antiabortion groups moved quickly to distance themselves from the killing. Outside Tiller's clinic, the Kansas Coalition for Life placed signs saying members had prayed for Tiller's change of heart, "not his murder."

In Washington, Attorney General Eric H. Holder Jr. ordered increased security yesterday at some clinics.

Roeder's ex-wife said his extreme antigovernment beliefs contributed to the breakup of their marriage more than a decade ago. And Roeder's brother said he suffered from mental illness at various times in his life.

"However, none of us ever saw Scott as a person capable of or willing to take another person's life," his brother, David, said in a statement. "Our deepest regrets, prayers and sympathy go out to the Tiller family during this terrible time."

Roeder's family life began unraveling more than a decade ago when he got involved with antigovernment groups, and then became "very religious in an Old Testament, eye-for-an-eye way," his former wife, Lindsey Roeder, told the Associated Press.

"The antitax stuff came first, and then it grew and grew. He became very antiabortion," said Lindsey Roeder, who was married to Scott Roeder for 10 years but "strongly disagrees with his beliefs."

"That's all he cared about . . . antiabortion. 'The church is this. God is this,' " she said.

Lindsey Roeder said that the early years of the marriage were good and that Scott Roeder worked in an envelope factory. She said he moved out of their home after he became involved with the Freemen movement, an antigovernment group that discouraged the paying of taxes. The Roeders have one son, now 22. "When he moved out in 1994, I thought he was over the edge with that stuff," his ex-wife said. "He started falling apart."

More recently, someone using the name Scott Roeder had posted comments about Tiller on antiabortion Web sites, including one that referred to the doctor as the "concentration camp Mengele of our day" - a reference to the Nazi doctor who performed ghastly medical experiments on Jews and others at Auschwitz. The posting said Tiller "needs to be stopped before he and those who protect him bring judgment upon our nation."

In another posting, on an Operation Rescue Web site, Roeder suggested a visit to Tiller's church to "have much more of a presence and possibly ask questions of the Pastor, Deacons, Elders and members while there."

As more details of Roeder's life emerged yesterday, the antiabortion movement found itself on the defensive, with prominent leaders delicately distancing themselves from the accused killer while positioning their stand against abortion as one shared by a majority of Americans.

Already reeling from the failure to dominate last year's election and worried their cause won't be at the center of the hearings on President Obama's first Supreme Court nominee, antiabortion leaders feared that backlash from Tiller's murder could temporarily silence the abortion debate.

"In the immediate future, it makes it difficult to even speak about an issue we've been speaking about for 365 days a year," said Mary Kay Culp, executive director of Kansans for Life.

Kansans for Life and Operation Rescue, which is also based in Kansas, said Roeder did not belong or donate to either group.

Operation Rescue condemned the killing as vigilantism and "a cowardly act." But its founder, Randall Terry, stressed that the antiabortion movement should not tone down its rhetoric. He said that the gunman was wrong to kill Tiller, 67, but that abortion opponents bear no responsibility for the action.

Tiller was "a mass murderer and horrifically, he reaped what he sowed," Terry told the National Press Club in Washington.