Reaching a plea agreement for mass killer Jared Lee Loughner is one step.

Today, defense attorneys and prosecutors will need to accomplish the next: convince U.S. District Court Judge Larry A. Burns that Loughner, who has been forcibly medicated at a federal prison, is no longer mentally unfit for trial.

If Burns agrees, as legal experts expect, a formal change of plea hearing will follow. That's when those in the court could hear from the 23-year-old at length for the first time, as the judge questions him.

Loughner, who was brought to Tucson on Monday from a federal medical facility in Missouri, will be asked to admit that he shot and killed six people, including the top federal judge in Arizona, and wounded 13 others, including former Rep. Gabrielle Giffords.

He'll need to convince Burns he understands what is going on, what he's doing and what he did.