TUCSON - A 23-year-old college dropout accused of killing six people and wounding 13 others, including then-U.S. Congresswoman Gabrielle Giffords, in a Tucson shooting rampage last year was expected to plead guilty on Tuesday if a judge finds him mentally competent, a person familiar with the case said.

A federal judge has set a competency hearing for Jared Loughner for 11 a.m. local time in U.S. District Court in Tucson, to be followed by a change-of-plea hearing if he is found fit to stand trial.

Giffords, an Arizona Democrat seen as a rising star in the party, was holding one of her regular "Congress On Your Corner" events at a Tucson supermarket in January 2011 when she was shot through the head at close range. The six people killed in the shooting include a federal judge and a 9-year-old girl.

A source close to the case has told Reuters that Loughner, who is charged with 49 criminal counts including first-degree murder, is prepared to change his plea to guilty. A not guilty plea was entered on his behalf last year.

Few other details were available ahead of the hearing, but a plea agreement could potentially spare Loughner from facing the death penalty in the rampage.

The Los Angeles Times reported that psychiatric experts who have examined Loughner were expected to testify that he now understands the charges against him.