By ADRIAN SAINZ

Associated Press

MEMPHIS, Tenn. - A former prison guard charged in the fatal shootings of two Tennessee postal workers struggled to learn simple tasks such as cleaning his room and getting dressed on his own as a child, his mother said during a federal court hearing today.

Lois Montgomery testified in a hearing that will determine if her 49-year-old son, Chastain Montgomery, is eligible to face the death penalty if convicted at trial in the deaths of Paula Robinson and Judy Spray during a robbery at small-town post office in October 2010.

Defense attorneys argue that Montgomery is intellectually disabled and, under federal law, ineligible for the death penalty. A psychologist testified Monday that three IQ tests show Montgomery has mild intellectual disability.

Those claims are being challenged by federal prosecutors, who argue that a person cannot be found to be mentally disabled on IQ tests alone.

Montgomery's mother first took the stand Monday, but her testimony was interrupted by an outburst by her son. Montgomery abruptly stood up and began to speak before being grabbed by U.S. marshals and forced into a room adjacent to the courtroom.

Montgomery sat slumped in his chair during Tuesday's hearing, raising his head at times to look at his mother on the stand. He asked for a break when his mother began speaking about one night when he slept outside, on the ground, in the dead of winter, in the months after his father passed away.

Lois Montgomery has an illness that affects her voice, making her speech labored and hoarse. She became emotional during parts of her testimony.

She testified her son had trouble staying neat, tying his shoes and doing chores as a child, and he rarely spoke to people outside the family. He sometimes would hide in a closet in their home, she said.

"He was slow," she said. "You would tell him several times how to do things but he had trouble catching on."

Later, Lois Montgomery said her son went to a high school for slow learners. But he did attend college at the University of Tennessee-Martin and was able to hold jobs, including a long tenure at a West Tennessee prison, she said.

Robinson and Spray were working in the Henning post office when they were shot multiple times. Prosecutors say Montgomery and his 18-year-old son, Chastain Montgomery Jr., shot the women after robbing the post office of $63. The younger Montgomery was killed in a shootout with police four months later.

Montgomery has pleaded not guilty to two counts of killing a federal employee while committing a robbery and other charges. No trial date has been set.