The man accused of attempting to assassinate a US congresswoman in a shooting attack that killed six people has pleaded not guilty to federal charges.
Jared Loughner, 22, entered the pleas over the attempted assassination of US Representative Gabrielle Giffords and two aides.
Ms Giffords, who was shot in the head, is at a rehabilitation centre in Texas. Thirteen people were injured in the attack.
Mr Loughner, who has been in jail since the attack, arrived amid high security for the hearing, the BBC said.
State charges in the six deaths and other injuries are expected to follow.
The shooting on 8 January occurred at a meeting Ms Giffords, a Democrat, was holding for constituents at a supermarket in Tucson, Arizona.
Prosecutors have said Mr Loughner, who had been rejected by the US military due to drug use and suspended from a college amid concerns about his mental health, targeted Ms Giffords for assassination.
Mr Loughner is represented by Judy Clarke, a prominent defence lawyer who represented an infamous parcel bomber and the man convicted of setting a bomb at the 1996 Olympic games in Atlanta.