WASHINGTON — Even as the authorities say they remain uncertain what precisely led a gunman to attack a Planned Parenthood facility in Colorado Springs on Friday, a comment attributed to the suspect by a senior law enforcement official — “no more baby parts” — fed directly into an already high-pitched controversy over Planned Parenthood and its practices.

The phrase was an eerie echo of language used by politicians here and in many state capitals since an anti-abortion group began releasing its undercover videos of Planned Parenthood officials discussing possible donations of fetal tissue for medical research.

Congressional supporters and opponents of Planned Parenthood were uncharacteristically subdued over the weekend as they awaited more information about the shooting, which killed three people and wounded nine, so it was unclear how the episode might affect Congress’s year-end agenda after lawmakers return on Monday from their holiday recess. But considering the extent to which Planned Parenthood has fomented political passions on both the left and the right in Washington, that restraint seems unlikely to hold.

Long before Friday, Planned Parenthood was expected to be prominent in the debate over legislation to finance federal operations, which the Republican-controlled Congress must pass before Dec. 11 to keep the government open. Anti-abortion conservatives want Republican leaders to let the government shut down unless President Obama agrees to end reimbursements to Planned Parenthood for health services to low-income patients. (These services do not include abortions, because federal law bans payment for most abortions.)

Five congressional committees have been investigating Planned Parenthood since a California-based anti-abortion group called the Center for Medical Progress in July started posting 11 videos online, one at a time over several months, purporting to show that Planned Parenthood was trafficking in “baby parts” for profit. Planned Parenthood has denied that.

John A. Boehner resigned as House speaker days after creating a special committee to investigate Planned Parenthood, other abortion providers and tissue procurement businesses. His decision to quit was forced by hard-line conservatives’ credible threat to unseat him for refusing to lead a government shutdown over Planned Parenthood funding. His successor, Representative Paul D. Ryan of Wisconsin, did not address the shootings over the weekend. But a spokesman, Brendan Buck, said on Sunday that the tragedy would not change the investigating committee’s plans.

On Saturday, Senator Barbara Boxer, Democrat of California, called on Mr. Ryan to disband the special House committee investigating Planned Parenthood. “It is time to stop the demonizing and witch hunts against Planned Parenthood, its staff and patients, and the lifesaving health care it provides to millions every day,” she said. Representative Marsha Blackburn, Republican of Tennessee, the chairwoman of what is called the Select Investigative Panel on Infant Lives, said in a statement that Mrs. Boxer should stop “playing politics with this tragedy.”

Investigators are interviewing friends, associates and family members of the suspected gunman, Robert L. Dear Jr., to determine whether he had ties to any extremist groups or if anyone helped him plot the attack, according to senior law enforcement officials. The authorities also want to know whether Mr. Dear told anyone about the plot in recent weeks, the officials said. So far, the authorities have found no evidence that he had help from anyone, the officials said. They also said they did not know if the suspect had any political motivations.

Prominent Democrats, including Mr. Obama and the House Democratic leader, Representative Nancy Pelosi of California, initially reacted to the shootings by reiterating their frequent calls for gun safety legislation, not by suggesting that abortion opponents’ attacks on Planned Parenthood might have been incendiary. They were awaiting more information about the shooter and his motivations, Democratic aides said. Others, however, sought to draw a connection between the fiery language used against Planned Parenthood and the potential for violence.

On the ABC News program “This Week” on Sunday, the head of Planned Parenthood of the Rocky Mountains, Vicki Cowart, lamented the “hateful speech” of recent months among legislators and Republican presidential candidates. “I can’t believe that this isn’t contributing to some folks, mentally unwell or not, thinking that it’s O.K. to target Planned Parenthood or to target abortion providers,” she said.