State prosecutors and the defense team disagree whether a 12-year-old girl accused of manslaughter of an infant is ready to stand trial, the third time the question has been considered since the infant’s death in 2012.

Kelli Murphy, of Fairfield, was charged in September 2012 with manslaughter of 3-month-old Brooklyn Foss-Greenaway, of Fairfield, who died at the home of Murphy’s mother, Amanda Huard, in July 2012. Murphy, who is the youngest manslaughter defendant in the state in at least 25 years, was 10 years old at the time.

In March, and again in June, the Skowhegan District Court found Murphy was not competent to stand trial. Judge Charles LaVerdiere said in June that he expected Murphy would be ready to face the charge in the foreseeable future. State investigators said in late June they would re-examine her competence in six months.

Assistant Attorney General Andrew Benson said Friday that the state believes that Murphy “has the skills required for competence.”

In order to be found competent, defendants must be able to understand the charges against them and how they relate to their actions, among other criteria.

Benson made the argument that Murphy was competent in March, but the court disagreed. Benson said there is more evidence that she is now able to stand trial. “I think her skills have developed since then.” Benson said. “Things have certainly changed in terms of her improvement of the skills associated with competence.”

But John Martin, Murphy’s lawyer, said Friday he doesn’t agree, though he acknowledges Murphy has shown some growth. “Clearly, any juvenile, day by day, is going to become more competent, obviously,” he said.

Still, he said, on the key questions that determine whether someone is competent, Murphy is no further along than she was six months ago.

“It’s our position that a lot of the factors that are looked at have not changed” since Murphy was first evaluated, Martin said.

On the night of July 8, 2012, Huard, who was babysitting Foss-Greenaway at her Fairfield home, made a 911 call to police and said the baby was not breathing.

The baby’s mother, Nicole Greenaway, of Clinton, said police investigators told her that her daughter had been suffocated and had traces of a medication prescribed to Murphy in her system.

Martin said a hearing on the matter was initially scheduled for Jan. 23, but that he requested it be delayed because a psychologist was not ready to submit an opinion to the court.

“We have an expert working on the defense team,” Martin said. “We needed more time for her report.”

The court rescheduled the hearing for March 27.

Martin and Benson both agreed that Murphy’s age was the main thing preventing her from standing trial.

“A large part of the reason she was found incompetent was due to her age,” Martin said, while Benson called age “the biggest single factor.”

Matt Hongoltz-Hetling — 861-9287 mhhetling@centralmaine.com Twitter: @hh_matt