Authorities have identified a little girl known as Baby Doe whose body was found in a trash bag on a Boston beach three months ago, and her mother was reported to be under arrest on Friday.

The girl’s name was Bella Bond, said Robert DeLeo, the speaker of the Massachusetts House. Sources told WHDH, the NBC affiliate in Boston, that the girl was about to turn 3 years old.

WHDH, citing unidentified sources, reported that the girl’s mother, Rachelle Bond, was arrested Friday. The cause of the girl’s death had yet to be determined, and there was no information on what charges might be filed. Boston authorities scheduled a media briefing for 5 p.m. Friday.

Gov. Charlie Baker said child-services workers had had contact with the girl twice, in 2012 and 2013, and that both cases were closed.

Police learned the girl’s identity after searching a Boston home on Thursday night, WHDH reported.

The identification appeared to resolve a mystery that drew wide attention. A social media campaign sought to figure out what had happened to the girl. Billboards across the city displayed a computer-generated image of her and asked: “Did You Know Me?”

The girl’s body was found in a bag on Deer Island in Boston Harbor on June 25. The girl was dressed in white pants with black polka dots, and a zebra-print blanket was left in the bag.

Investigators analyzed pollen found clinging to her pants to determine that she probably lived in the area.

RELATED: Pollen Analysis Reveals Girl Found Dead on Deer Island Was Likely a Local

“The amount and the types of pollen that were on those items suggest that she was from the Boston area,” Jake Wark, spokesman for Suffolk County District Attorney Dan Conley, told NBC News. “That’s somewhat reassuring, because that’s been a theory from the start.”

RELATED: ‘Baby Doe’ Discovery on Deer Island in Boston Harbor Mystifies Authorities

Because Baby Doe’s body was only in the early stages of decomposition, detectives thought she had been killed not long before she was found. The pollen analysis buoyed suspicions that Baby Doe was placed on Deer Island, rather than the idea that she washed up there after drifting from a faraway coastline.

The girl had pierced ears and appeared to be well-nourished.