Washington » Judy Clarke’s client list reads like a who’s who of America’s infamous murder and terrorism convicts, from Susan Smith, who drowned her children, to "Unabomber" Ted Kaczynski, to the so-called 20th hijacker who didn’t make it onto the planes that struck on Sept. 11, 2001.

Though those defendants were convicted and sentenced to prison, Clarke, a former president of the National Association of Criminal Defense Lawyers, has developed a reputation as an expert on asserting mental disability as a defense, and has managed to keep many killers off death row.

Her newest assignment is Jared Loughner, charged with the attempted assassination of U.S. Rep. Gabrielle Giffords and the murder of U.S. District Judge John Roll. Clarke was appointed today to represent Loughner in Phoenix federal court.

The Federal Public Defender’s Office in Arizona asked a Phoenix judge to appoint Clarke lead attorney for Loughner, who could face the death penalty if convicted.

Clarke, a former U.S. public defender in San Diego and Spokane, Wash., now in private practice in San Diego, is known as an expert on death penalty cases, especially those where mental illness is an issue.

"There are very few attorneys in the country with her degree of experience," said Karen Hewitt, a former U.S. attorney for San Diego. "In a case like this that is fraught with emotion and is such a difficult case, she seems to be the prime person to handle it."

Heather Williams, first assistant federal public defender for Arizona, said Clarke was asked to take the case after Williams’ office found there could be an appearance of a conflict of interest because its attorneys practiced before Roll, who was chief judge for the Arizona federal courts.

Clarke declined to comment, according to the defender’s office.

Additionally, Williams said, the state does not have many attorneys who are qualified to handle death penalty cases.

"We wanted to get someone who was not far away and who would not have a conflict of interest," Williams said. "She was available, she’s experienced in death penalty cases and she was willing to undertake the representation."

Lawyers who have worked with Clarke describe her as a "straight shooter" with little ego and no agenda other than defending her clients. Most of the death penalty-eligible cases she has handled, these lawyers said, resulted in plea agreements before trial.