Scott Roeder called The Associated Press from the Sedgwick County jail, where he's being held on charges of first-degree murder and aggravated assault in the shooting of Dr. George Tiller one week ago.
"I know there are many other similar events planned around the country as long as abortion remains legal," Roeder said. When asked by the AP what he meant and if he was referring to another shooting, he refused to elaborate further.
It wasn't clear whether Roeder knew of any impending violence or whether he was simply seeking publicity for his cause. Law enforcement authorities including the Justice Department said they didn't know whether the threat was credible.
Tiller's clinic in Wichita was among only a few in the U.S. that perform third-trimester abortions. He was shot while serving as an usher at the Lutheran church he attended.
Asked if he shot Tiller, Roeder replied that he could not comment about that and said he needed to clear everything with his lawyer.
Justice Department spokesman Matthew Miller said in a written statement Sunday that "we take this matter seriously, which is why the Attorney General ordered increased protection of appropriate people and facilities last week."
Tiller's clinic had been a target of regular demonstrations by abortion opponents. Most were peaceful, but his clinic was bombed in 1986 and he was shot in both arms in 1993. In 1991, a 45-day "Summer of Mercy" campaign organized by Operation Rescue drew thousands of abortion opponents to Wichita, and there were more than 2,700 arrests.
The Justice Department opened an investigation Friday to see if the gunman who killed Tiller had accomplices. The DOJ said its Civil Rights Division and the U.S. attorney's office in Kansas will investigate whether the killing violated a 1994 law creating criminal penalties for violent or damaging conduct toward abortion providers and their patients.
An attorney for the Tiller family, Dan Monnat, said he wasn't sure they should be dignifying Roeder's actions and threats with a response "every time he makes a hare-brained phone call."
"I am hopeful that state and federal authorities, including Homeland Security, will give Mr. Roeder and his information a deserving response," Monnat said, declining to elaborate.
Nancy Keenan president of NARAL-Pro-Choice America, said Roeder's comments "continue to escalate that kind of activity, that kind of violence. Quite honestly, I think it's imperative for anti-choice groups to tone down that rhetoric and keep the more extreme elements in their movement form copying Scott Roeder."
A funeral was held Saturday for Tiller. Most anti-abortion groups avoided the service, having denounced Tiller's shooting.