FAIRFIELD, Maine — A 10-year-old girl has been charged with manslaughter in connection with the death of a 3-month-old baby girl last month.

Brooklyn Foss-Greenaway of Clinton died on July 8 while under the care of a baby sitter in Fairfield. Maine State Police declared the death a homicide on Wednesday.

The infant’s mother, Nicole Greenaway, said a toxicology report stated that a medication was found in her infant’s system which was the same as the medication taken by the 10-year-old girl, who is the daughter of the baby sitter.

“She [also] suffocated her by putting her hands over her face,” Greenaway said Thursday night. “There are bruises all over her face.”

The mother of the 10-year-old declined to comment Thursday night, referring inquiries to her attorney, John Martin of Skowhegan. The Bangor Daily News is not naming the mother in order to protect the identity of the juvenile charged with manslaughter. Police have also withheld the girl’s name.

Maine Department of Public Safety spokesman Stephen McCausland would not disclose how the girl caused the baby’s death.

“We’re not discussing her role or getting into any more details on her identity, although we feel she is responsible for the baby’s death,” said McCausland. “Manslaughter was the appropriate charge.”

Martin, the 10-year-old girl’s attorney, was served with a court summons Thursday afternoon, McCausland said in a press release. The girl is scheduled to appear in Skowhegan District Court on Oct. 22.

Martin did not return a phone message left by the Bangor Daily News on Thursday afternoon.

Nicole Greenaway said the 10-year-old is the daughter of a woman she works with at MaineGeneral Medical Center in Waterville. Greenaway said the woman was baby-sitting Brooklyn before she died.

“I’m definitely glad they’re finally doing something,” Greenaway said earlier Thursday in a telephone interview. “I just didn’t know when they were going to do it. [The last couple of days have been] pretty overwhelming.”

Greenaway, who has three other children, ages 2, 15 and 16, said the last two months have been full of “a lot of heartache and a lot of patience.”

The 10-year-old girl is now in custody of the Maine Department of Health and Human Services, McCausland said.

“The decision on charging the girl was made after consulting with the attorney general’s office,” said McCausland. “The state medical examiner’s office continues to work on the case.”

McCausland said the girl is the youngest person in Maine to be charged with manslaughter in at least 25 years.

“I have not done any research farther out than that,” he said.

The death of any child under age 3 automatically triggers an investigation in Maine.

The baby’s parents live in Clinton and had arranged for the child to spend the night at the baby sitter’s Fairfield home, according to The Associated Press.

Emergency officials arrived just six minutes after receiving a call in the early morning hours that the child was unresponsive and not breathing.

Augusta lawyer Walter McKee, who has defended juveniles charged with manslaughter, said such cases can follow two paths. The case can stay in juvenile court or be transferred to Superior Court, where the juvenile would be tried as an adult.

McKee represented Patrick Armstrong, who in 2005, at the age of 14, struck neighbor Marlee Johnston, 14, in the back of the head several times with an aluminum baseball bat in Fayette. Armstrong pleaded guilty to manslaughter in 2006 and was sentenced to 25 years in prison with all but 16 years suspended.

But McKee said he couldn’t fathom how a 10-year-old could be tried as an adult.

“Regardless of what court it goes to, there would be significant issues of whether the child had the brainpower to have the state of mind to commit the crime,” said McKee. “This is a hotly discussed topic now.”

McKee said the brain of a prepubescent child, such a 10-year-old, is far less developed than that of an adult.

“It’s not [an] apples and oranges [comparison],” he said. “It’s apples to carburetors — the furthest away from a fruit you can get.”

McKee said there have been cases in which a juvenile is placed in a juvenile detention facility, such as Mountain View Youth Development Center in Charleston, until the age of 21 and then is transferred to an adult prison.