Jason Derek Brown's strikingly average looks help him hide from the FBI.

The 43-year-old has eluded the agency since allegedly murdering armored truck driver Robert Keith Palomores in 2004, and his ability to blend in has been his biggest asset, Agent Lance Leising told the Salt Lake Tribune.

"With the commonness of his name and how he looks, like a surfer dude in California, we’ve had more tips [about this] fugitive than any other on ‘America’s Most Wanted,'" Leising said.

On two separate occasions, those tips have led the FBI to a body double for Sean Penn.

In addition to first-degree murder, Brown is charged with armed robbery and unlawful flight to avoid prosecution. Authorities say that after shooting Palomares, he made off with $56,000 on a getaway mountain bike.

Prior to the murder, Brown was a Mormon missionary, and the FBI now believes he may be hiding within the Mormon community.

"It's a possibility because of Jason's familiarity with the Mormon Church," Special Agent Manuel Johnson told ABCNews.com. "Prior to the shooting he was involved in different types of fraud, so he's not who he claims to be and we could see him taking advantage of people."

Brown is described as 5-foot-10, weighing between 170 to 180 pounds, with green eyes and blond hair. The FBI is offering a reward of up to $100,000 for information leading to his arrest.

CORRECTION: A previous version of this article incorrectly listed one of Brown's charges as "unlawful flight to avoid persecution." The correct charge is unlawful flight to avoid prosecution.