HAMILTON, Mont. -

The man who faces federal charges for allegedly threatening President Obama and his family had been cleared to carry a concealed weapon, and had reportedly taken a gun to work.

Now, the Valley Veterans Service Center, where Dan Rachell worked before an internal investigation closed the center for a time, has put up a sign at its door banning weapons.

The incident has sparked concerns over people with a history of violence and mental illness who are issued concealed weapons.

Rachell had been involuntarily committed in another state for allegedly making violent threats.

Hamilton mental health advocate Kathleen Driscoll said most people struggling with mental illness are not violent. But she said if a person's core personality is violent and you layer mental illness on top of it, violence may break through.

With Rachell's history, said Driscoll, he should never have been approved for a concealed weapon.

"Things were out of control in his life," she said, "and he was able to get a gun. People are right -- guns don't kill people, but availability of guns do kill people."

NBC Montana asked Ravalli County Sheriff Chris Hoffman if they could have prevented Rachell from obtaining a concealed weapon permit.

Hoffman said if he was aware of an adjudication of his mental health status, or if there was an active criminal case against him, or if a judge had taken away his right to own a firearm, then the sheriff would not have issued the permit.

The sheriff said every permit is looked at carefully. But he said as they examine these applications there are things the sheriff isn't privy to, such as a mental health evaluation.