McCarthy, the one-time boyfriend of the girl's mother, Rachelle Bond, was found guilty Monday of second-degree murder
in a trial that lasted about a month. Prosecutors said McCarthy killed Bella and said she was a "demon,"
and then went on a heroin binge with Rachelle Bond for months.
McCarthy's attorneys said the allegations were largely based on testimony from Rachelle Bond, who they described as a "scheming, manipulative woman" who lied about her daughter's death to cover up her own guilt.
In Massachusetts, a second-degree murder conviction carries a mandatory sentence of life in prison, with parole eligibility in 15 to 25 years.
Prosecutors said McCarthy shouldn't be eligible for parole until after 25 years in prison, while the defense sought parole eligibility after 15 years. The judge split the difference in her ruling.
Bella 'always will be in my heart and soul'
Joseph Amoroso, Bella's father, read aloud a statement Wednesday at McCarthy's sentencing lamenting the lost possibilities.
"Bella was a happy and innocent child full of light. She was very smart and learned things rather quickly. She loved Hello Kitty, and she also knew how to make a pizza," Amoroso said.
"Bella was a gift from God whose life was cut short at such a young age, but Bella was, still is and always will be in my heart and soul."
Amoroso, who moved away shortly before the child's birth, never met his daughter but would talk to her over the phone, he testified during the trial. He visited Bond's home in Boston in September 2015 hoping to meet his daughter, but he was too late.
"I was robbed of my chance to be a father of Bella. No verdict changes that, and no justice on earth fixes that grief," he said.
Months-long search for child
The guilty verdict and life sentence capped a disturbing story that began in June 2015 when a jogger found an unidentified girl's remains in a trash bag along Deer Island near Boston. Authorities launched an extensive effort to identify the girl, known as "Baby Doe," and commissioned an artist to draw a composite image of her that was widely shared.
The case broke open in September 2015 when Bond admitted to a friend that Bella was dead, and not, as she had told others, taken away by the state's Department of Children and Families. That friend realized Bella was "Baby Doe" and told police, leading to the arrests of McCarthy and Bond.
In exchange for her testimony against McCarthy, Bond was sentenced to time served and is expected to be released on probation.
The trial focused on the rampant drug addiction that consumed almost every adult close to Bella.
"(It's) primarily heroin that led us all here," Assistant District Attorney David Deakin said in closing arguments. "If there weren't heroin in this case, there wouldn't be a case."