Mourners visit a makeshift memorial Aug. 12, 2019, near the Walmart in El Paso where 22 people were killed in a shooting that police are investigating as a racially motivated terrorist attack. The FBI and Justice Department have faced criticism for not addressing white supremacy and other domestic extremism as aggressively as they do international terrorism. (Cedar Attanasio/AP)

An Ohio woman who authorities say corresponded in prison with Charleston, S.C., church shooter Dylann Roof and plotted mass violence pleaded guilty Tuesday to a terrorism charge in a case that a top federal prosecutor said could serve as a model to pursue white supremacists or other domestic extremists.

Elizabeth Lecron, 24, pleaded guilty in federal court in Toledo to providing material support to terrorists and transporting explosives in interstate commerce, agreeing to spend 15 years in federal prison and be subjected to a lifetime of supervision by federal authorities after she is released.

Justin E. Herdman, the U.S. attorney for the Northern District of Ohio, said he had never used the terrorism charge outside of an international context in his seven years as a national security prosecutor, from 2006 to 2013. But in Lecron’s case, he said, he was able to do so because it involved explosives. Herdman said he’s hopeful that other prosecutors might consider similar charges in domestic extremism cases.

“We are dusting off our books, cracking them open and looking through it to find statutes that can apply where we are concerned about an ongoing threat and disrupting a threat,” Herdman said. “And obviously, at the heart of this case, that’s what it’s all about — it’s disrupting threats.”

Attorneys for Lecron did not immediately respond to an email seeking comment.

In part because of a recent massacre at a shopping center in El Paso that was racially motivated, the FBI and Justice Department have faced criticism for not addressing white supremacy and other domestic extremism as aggressively as they do international terrorism. The FBI saw a major increase in tips in the wake of that and another mass shooting in Dayton, Ohio.

Officials have sought to stress that they take all security threats seriously, while noting that the law gives them more authority to go after international terrorist groups.

Those who merely send resources to specifically designated international groups, such as the Islamic State, can face federal charges for providing material support to terrorists. But domestic groups cannot be designated as terrorist organizations to which providing resources would be a crime because that would raise concerns about freedom of speech or association.

Federal prosecutors can, however, charge domestic extremists with providing material support to terrorists if they engage in specific plots — such as those that involve aircraft, explosives, chemical weapons or federal property. Federal prosecutors used the charge this year against five people living in a New Mexico compound, alleging that the group trained in its squalid quarters to kill FBI and military personnel. The indictment did not identify any particular terrorist organization the group allegedly sought to support.

Herdman said the material support charge is valuable in part because it allows prosecutors to seek a lifetime of supervised release, which can be important in preventing mass violence from being committed by those who have shown a propensity for it.

“It is a tool that is clearly available to us, with the right set of facts,” Herdman said. “Up until this point, it really hasn’t been, but you’ve got to have those facts to be able to make it out.”

Police first received a tip in the summer of 2018 about Lecron’s boyfriend, Vincent Armstrong, who pleaded guilty this month to conspiring to transport or receive an explosive. Investigators soon began exploring troubling social media posts from Lecron, whom Herdman termed the “leader” of the pair.

Lecron seemed to broadly idolize mass murderers, posting online about them frequently and, with Armstrong, visiting Columbine High School, where 12 students and a teacher were killed in 1999.

When investigators searched the home she and Armstrong shared last August, they found an AK-47, a shotgun, multiple handguns and ammunition, as well as end caps, which can be used to make pipe bombs, authorities have said. They connected Lecron with a confidential informant and undercover FBI agents, to whom she talked about committing “upscale mass murder” at a Toledo bar or bombing a pipeline.

At the informant’s suggestion, she bought explosive powder and hundreds of screws, according to an affidavit in the case. And all the while, she was corresponding with Roof and attempting to send him Nazi literature, prosecutors said.

Herdman said Lecron had an “either overbroad or nonexistent” ideological motivation.

The material-support charge has its limits for domestic terrorism, he said. It cannot be used, for example, if only firearms are being employed in such a plot. If an attack is carried out, federal prosecutors can often bring hate-crime, weapons or other charges that carry more significant jail time.

But Herdman said it can be used to disrupt plots — as Lecron’s case shows.

“It really is a road map for how we can disrupt or intervene at an earlier point,” he said.