"Short of developing a technique for a complete brain transplant, there is no hope that medical treatment will be discovered in the foreseeable future which could reverse" her condition, a doctor said, according to court records.
On Jan. 17, 2006, the state's Supreme Judicial Court said it would allow DSS to take Haleigh off the ventilator that was keeping her alive.
But before doctors took any action, Haleigh reportedly began breathing on her own. Avrett, who was still visiting Haleigh at the time, told ABC News that her daughter's eyes began following her around the room and would blink in response to questions.
Haleigh is now in rehabilitation at the Franciscan Hospital for Children near Boston, though her level of recovery is not clear. Wendy Murphy, Avrett's attorney, said Haleigh is enrolled at the day school at the hospital.
Though she has not seen Haleigh recently, Murphy said she was told the girl is able to communicate through a keyboard and speak some words. The Boston Globe, citing an anonymous source with knowledge of the girl's care, reported similar information.
Though the girl's recovery is unusual, Larry Goldstein, director of the Center for Cerebrovascular Disease at Duke University Medical Center, said there have been other reported cases of people recovering from persistent vegetative states within a few months.
"It's unusual, but not unheard of," he said.
Haleigh has been at the hospital for more than two years, and her future remains uncertain.
Avrett, who gave birth to Haleigh when she was 17, gave up custody of her daughter four years later. The DSS had accused her of being an unfit mother, in part because of an allegation that her then-boyfriend had sexually abused Haleigh.
Avrett's sister Holli Strickland became Haleigh's adoptive mother. She was also charged in the September 2005 attack that left the girl comatose. Eleven days later, she died in what was ruled a murder-suicide pact with her grandmother.
According to the Globe, citing an anonymous source, Haleigh began to express fears about seeing Avrett, after the woman began paying regular visits to her biological daughter. Avrett told ABC News that her visits were suspended in July 2006.
Avrett said she was never given an explanation for ending her visits and called the allegation that Haleigh was afraid of her "outrageous."
"I never saw any signs of that," she said. "She smiled."
Murphy said DSS told Avrett not to speak publicly about the case and said that her visits were suspended in retaliation for criticizing the department. Avrett has sued DSS to reinstate her visits.
A Social Services spokesman declined to comment on the case, citing a judge's gag order. The Hampden County, Mass., district attorney's office also declined to comment.
Legal experts said they expected Haleigh's injuries to be an issue in the trial, should she take the stand. Though Haleigh's case is unusual, similar legal issues arise when a young child testifies or when a witness claims to recall suppressed memories, said Brad Bailey, a former prosecutor in Boston.
Bailey said he would expect a judge to hold a hearing to determine whether Haleigh's memories are reliable and free from outside influences.
Avrett's old boyfriend, who was accused of sexually abusing Haleigh, was also named Jason, though Murphy said Haleigh called him Daddy J.
A judge would also want to make sure that Haleigh is capable of understanding her surroundings, understands the difference between the truth and a lie and the consequences of lying, Bailey said.
Avrett says the possibility of convicting Strickland is not worth having Haleigh testify.
"I want for her to be able to heal and be left alone," she said.