ARLINGTON, Va. — The Ethiopian jail guard suspected of torturing and maiming political prisoners during that country’s “Red Terror” era came to the United States in 2004 under a false identity, seeking asylum and claiming he would be persecuted if he returned home.

He lived comfortably in Denver until one day in 2011 when another Ethiopian who recognized him outside a cafe confronted him with the words, “I think I know you.”

And that’s how Kefelegne Alemu Worku, convicted last year of identity theft and immigration fraud, came to the attention of federal law enforcement authorities.

The government would like to see that happen more often.

A Justice Department lawyer recounted Worku’s case at a recent presentation for refugee advocates, part of an outreach to encourage the reporting of human-rights abusers hiding in plain sight. The hope is to raise the profile of a relatively new prosecution unit and to make refugees comfortable with helping investigators — a major challenge in human-rights criminal cases.