Story highlights Mom's boyfriend alleged to have punched child because he thought she was possessed, source says

Police arrest Rachelle Bond, the girl's mother, and her boyfriend, Michael McCarthy

"This child, whose very name means beauty, was murdered," prosecutor says

(CNN) Before the end of her short life, little Bella Bond was allegedly punched by her mother's boyfriend because he thought she was possessed, a law enforcement source involved in the investigation told CNN on Saturday.

It's unclear whether the punches killed the toddler who became known as "Baby Doe" after her remains, wrapped in a trash bag, were found in June on a rocky shoreline in Boston Harbor.

"The tragedy of her death is compounded by the fact that her short life ended not by illness or accident, but we believe by an act of violence in the very place where she should have felt safest, in her home," Suffolk County District Attorney Daniel Conley said.

Michael McCarthy, who is not Bella's biological father, and the girl's mother, Rachelle Bond, were arrested this week in connection with the death.

"We allege that McCarthy caused Bella's death, that he did so intentionally, that he and Bond took specific steps to keep Bella's death a secret and to avoid prosecution," Conley said.

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