DHS chief 'very concerned' about ISIS copycats

Homeland Security Secretary Jeh Johnson said on Friday that he is "very concerned" about ISIS-inspired copycat attacks in the U.S., but that does not seem to be the principle factor in a high-profile Oklahoma beheading.

In that case, police say Alton Nolen killed a co-worker after being fired from a food processing plant on Sept. 25. The FBI found no links to terrorism in a probe of Nolen, who is being tried for first-degree murder.

"He very clearly was somebody who was looking at the extremist ideology, had to some degree, and I don’t really know exactly how much, this is a matter for law enforcement, to some degree had embraced it, and there is no evidence at this point that he was directed by a terrorist organization to do what he did or that that was the principle motivating factor," Johnson said on Fox News.

Texas Gov. Rick Perry (R), a possible presidential candidate who has also raised the possibility of ISIS militants crossing into the U.S. from Mexico, said this week that the Obama administration should treat the incident as "associated with terrorism."

Johnson said that he travels the country as part of a program to prevent people in the U.S. from being inspired by terrorist groups. 

"These terrorist groups have very slick social media, propaganda and literature that have the capability of inspiring somebody whose never met a member of the group or been to a terrorist training camp, and so we’re very concerned about the possibility of that and we’re addressing it," he said.

Johnson also batted down a question about reports of four men with ties to terrorists being detained at the U.S. border with Mexico last month. 

"There was no evidence that we could determine that these individuals were tied to terrorist organizations," he said. 

He said they are still being detained, because they are undocumented immigrants.