Why was Jared Loughner assigned a special public defender??

Why was Jared Loughner assigned a special public defender??
Recently, Jared Lougher, was arrested for murder and attempted assassination of Congresswoman Gabrielle Giffords. Why was it necessary to assign him a special public defender, Judy Clarke? My understanding is she has defended homegrown domestic terrorist like the Unabomber and Timothy McVeigh.