A man has been arrested in connection with a small explosion near the offices of the Colorado Springs chapter of the NAACP.

A law enforcement source says 44-year-old Thaddeus Murphy was in custody Friday and was due to appear in federal court later in the day. The source spoke to The Associated Press only on condition anonymity because the information has not been publicly released.

The FBI investigated last month's explosion as a possible hate crime. However, it wasn't immediately clear what Murphy would be charged with or whether authorities believe he was targeting the NAACP office.

The chapter's office is in a building that houses other businesses, and the explosion happened on the opposite side of a building.

It caused only minor damage and no injuries but rattled nerves due to its proximity to the nation's oldest civil rights organization.