Eugene, Ore. - A man serving a 50-year prison sentence for beating his daughter into a coma could face an even stiffer sentence now that she has died.

If an autopsy determines that the injuries suffered by Stephanie Amber Moss led to her early death, Philip Lee Kephart could face an aggravated murder charge, said District Attorney Doug Harcleroad of Lane County.

"We need to pull out the old file and look at the documents," he said. "But there's no hurry; we'll get it sorted out. He's not going anywhere."

Moss went into a coma two months before her seventh birthday. She spent the rest of her life in a Eugene nursing home until her death Friday at age 23.

Called "Amber" by her mother's family, the child confounded medical opinions by regaining consciousness. But the extensive brain damage prevented her from speaking or using her limbs.

Concerned relatives reported the abuse multiple times to child-welfare officials.

Amber endured months of torture before the beating that sent her into a coma, according to court records. A backhanded slap broke her nose and she was slammed headfirst into a wall, breaking the plaster. Her father grabbed her by throat with enough intensity to restrict her breathing and she was bound upright to the end of a bunk bed.

Concerned relatives reported the abuse multiple times to child-welfare officials, who had placed Amber with Kephart after she was removed from her mother's place because of the woman's drug use.

Amanda Couturier, Amber's 9-year-old stepsister, also endured abuse at Kephart's hands. Amanda was bound and struck on several occasions. Her mother, Lisa Kephart, was convicted of felony criminal mistreatment for failure to protect Amber and Amanda.

Amber remained in state custody until her 21st birthday, when responsibility of her care shifted from children's services to adult disability programs.

She "learned quite a bit" from sessions with tutors at the nursing home, said her grandmother, Barbara Moss, who devoted 16 years to visiting and nurturing the girl with talk, songs, toys and stylish clothing.

"She worked on activities and communicated in the way that she could," which included blinking her eyes to indicate "yes" and making a clicking noise with her tongue for "no," she said.

Amber will be buried "in a pretty, white lace dress - it's strapless, so we bought her a little wrap to wear with it," Moss said. "We're trying to give her what she didn't have, what she couldn't wear before."