Boston's 'Baby Doe' identified, source says

(CNN)The girl known as "Baby Doe" -- who in June was found dead, wrapped in a trash bag on a rocky shoreline in Boston Harbor -- has been identified by authorities, a law enforcement source said Friday.

A suspect was taken into custody in connection with the case after a search warrant was executed in Boston's Mattapan neighborhood on Thursday, the source told CNN.

The man being questioned by authorities is the boyfriend of the mother of "Baby Doe," the law enforcement source said. It's unclear if the man -- who has not been charged -- has a lawyer or if he's cooperating, according to the source.

The child's identity has not been released, according to the source.

Authorities were to hold a news conference later Friday, the source said.

The case of the mysterious girl, whose adorable brown eyes and cherubic face -- as rendered by forensic artist Christi Andrews and distributed by authorities in Massachusetts -- caught the attention of millions.

The Suffolk County District Attorney's office told CNN that the "investigation remains very active" but that it had no update to share.

The tiny remains were found June 25 wrapped in a black trash bag, wearing polka dot pants lying next to a zebra blanket along the shore of Deer Island, a narrow peninsula just east of Boston's Logan Airport. Police released photos of the blanket and the polka-dot leggings she was wearing.

Authorities previously said they believe that "Baby Doe" was about 4 years old at the time of her death. She was 3 feet 6 inches tall and weighed about 30 pounds.

The National Center for Missing & Exploited Children released the composite of Baby Doe in July. Massachusetts State Police posted it on Facebook and distributed it via Twitter.

More than 50 million people saw or shared the composite.

Her remains were discovered along the shore of Deer Island, which has a 2.6 mile recreational perimeter accessible to the public, according to the National Park Service. The island is near the Port of Boston, one of the busiest on the eastern seaboard.

It's unclear how long she had been dead but there was some decomposition when her remains were removed from the trash bag.

Authorities analyzed pollen found on the girl's pants and blanket and determined that it "came from trees and plants around Boston," Jake Wark, a spokesman for the Suffolk County District Attorney's Office, said last month.

"This pollen analysis also suggests that 'Baby Doe' may have been placed on the shoreline, rather than washed ashore from a great distance," Wark said.

CNN's Chuck Johnston and Jason Hanna contributed to this report.