KANSAS CITY, Missouri (Reuters) - A Kansas doctor reviled by anti-abortion groups for his work providing “late-term” abortions was shot and killed in his Wichita, Kansas church on Sunday, and police said they captured the man responsible.

Police said they planned to charge a 51-year-old man on Monday with homicide and two counts of aggravated assault in the death of 67-year-old George Tiller, who died from a single gunshot.

Tiller was shot while serving as an usher for Sunday services in the foyer at Reformation Lutheran Church. The shooter threatened two other men at the church who tried to intervene, police said.

“We feel that this is an act of an isolated individual, however our investigation continues,” said Wichita deputy police chief Tom Stolz.

Stolz said they were investigating whether the shooter had any ties to anti-abortion groups.

President Barack Obama expressed shock and outrage, saying in a statement, “However profound our differences as Americans over difficult issues such as abortion, they cannot be resolved by heinous acts of violence.”

U.S. Attorney General Eric Holder said federal law enforcement officials would work with local authorities in investigating the crime. He directed federal agents “to offer protection to other appropriate people and facilities around the nation.”

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The killing comes as the Obama administration is seeking confirmation to the U.S. Supreme Court of Sonia Sotomayor, whom many anti-abortion groups have vowed to oppose for her perceived support of the landmark Roe vs. Wade ruling that legalized abortion in the United States.

“For the movement, it could not come at a worse time,” the Rev. Patrick Mahoney, director of the Christian Defense Coalition, which lobbies against abortion, said of the killing.

“If they make it seem that people who embrace the pro-life movement are kind of this extremist violent group, that could diminish some of the passion and energy on confronting Sotomayor.”

Mahoney said that while it was likely Tiller’s killing was motivated by anti-abortion beliefs, the movement did not support violence. Anti-abortion leaders will hold a news conference in front of the U.S. Supreme Court at 10 a.m. EDT on Monday to discuss the matter.

Tiller was one of only a few physicians in the United States willing to perform late-term abortions, those performed after the 20th week of gestation when a fetus potentially could survive outside the womb and legal under certain conditions.

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PREVIOUS ATTACKS

Tiller’s Wichita clinic had been the site of several mass protests by anti-abortion groups and was bombed in 1985. The doctor was shot in both arms by an abortion opponent in 1993.

Abortion foes celebrated earlier this year when Tiller was brought to trial on charges of illegally performing certain abortions in his Wichita clinic. But he was acquitted in March.

One anti-abortion group, Operation Rescue, had been particularly outspoken against him, maintaining a “Tiller Watch” on its website. But the group on Sunday denounced “vigilantism” and said it was praying for Tiller’s family.

Police declined to name the suspect in Sunday’s shooting, saying only that he was captured a few hours after the killing about 180 miles north of Wichita, near Kansas City. Police said he was a resident of Merriam, Kansas, a suburb of Kansas City.

Tiller’s family released a statement through its lawyers calling the killing a “unspeakable tragedy.”

“This is particularly heart wrenching because George was shot down in his house of worship, a place of peace,” the statement said.