Attack Highlights Challenge of Pursuing Domestic Extremists

WASHINGTON (AP) — Federal authorities investigating the El Paso shooting call it an act of domestic terrorism, but they won't be able to apply the same terrorism law that prosecutors have used for years against supporters of the Islamic State and al-Qaida.

The federal government defines domestic terrorism as politically motivated violence designed to coerce or intimidate a civilian population. The assault on a shopping area seemed to qualify after the emergence of a rambling screed posted to an online message board about 20 minutes before the shooting. The note said the massacre was in response to an "invasion" of Hispanics coming across the southern border. Investigators increasingly believe those words were written by the suspect.

"We're going to do what we do to terrorists in this country, which is deliver swift and certain justice," U.S. Attorney John Bash, the top federal prosecutor in West Texas, said Sunday at a news conference.