BOSTON (CBS) — Opening statements were made and testimony began Tuesday morning in the trial of a man accused of killing a two-year-old girl whose image was circulated widely on social media after her body was found washed up on Deer Island in 2015.

Prosecutors say Michael McCarthy threatened to kill the mother of Bella Bond if she told anyone about the girl’s death, and called the girl “a demon”–while the defense claims it was the mother, Rachelle Bond, who killed her.

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Michael McCarthy. (WBZ-TV)

McCarthy is charged with first-degree murder in Bella Bond’s killing. The child was known for months only as “Baby Doe,” as authorities sought her true identity.

Rachelle Bond’s daughter Bella and the image of Baby Doe issed by police. (Facebook photo and State Police image)

McCarthy was dating and living with Rachelle Bond at the time of the girl’s death. Rachelle has agreed to testify for the prosecution in exchange for a guilty plea in the case.

She pleaded guilty to helping dispose of her daughter’s body.

Michael McCarthy and Rachelle Bond. (Photos Suffolk DA/RMV)

In his opening statements, prosecutor David Deakin told the jury that McCarthy and Bond met when they were addicts living on the street, and that Bond was trying to clean up her life until meeting him.

Bond was impressed, Deakin said, with McCarthy’s interest in alternative spirituality and the supernatural.

But Deakin said McCarthy struck Bella one night, and that afterward, she wasn’t moving or breathing. Some time later, Deakin said, McCarthy told Bond to get in the car, and drove to South Boston, where he threw a duffel bag containing Bella’s body into the water.

Prosecutors say that, in the spot where Rachelle said her daughter’s body was dumped, divers found weights that matched the kind found in McCarthy’s father’s office.

“After they parked the car, she realized that he was no longer in the car, and neither was the bag or the weights,” Deakin said. “He came back a short time later empty-handed, and she knew what he had done with her daughter’s body.”

The body of the little girl was found washed ashore in a trash bag on Deer Island by Bonnie Flynn, a Winthrop woman who was walking her dog.

Flynn was the first witness called in the case Tuesday. In her emotional testimony, she said told the court through tears how she opened the bag using a seashell after her dog began circling it.

“I looked away thinking that it wasn’t real,” Flynn told the court.

Composite, computer-generated images of the child were shared widely by police through social media.

Marilin Santana, who was a Dorchester neighbor of Rachelle Bond and Michael McCarthy and said she stopped seeing little Bella in May or June of 2015, testified Tuesday that she saw those photos but didn’t connect them to the child.

The girl remained unidentified until prosecutors say Rachelle Bond texted a friend of McCarthy three months after the child was found, saying that McCarthy had killed her. That friend went to the police, leading to McCarthy’s arrest.

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Deakin said Rachelle Bond didn’t report the murder because she was afraid of McCarthy.

“If you tell anyone, I will kill you … She just died. It was her time. She was a demon.” prosecutors say McCarthy told Rachelle Bond.

But McCarthy’s defense said McCarthy wasn’t even aware the girl was dead, and that he was “shocked” when troopers told him so.

“He is not guilty of killing Bella Bond,” defense attorney Jonathan Shapiro said at the start of his opening statements.

The defense claims there’s no surveillance or evidence pointing to McCarthy as the killer. They say the prosecution’s account relies entirely on the testimony of Rachelle Bond, who they claim is responsible for the girl’s death.

Shapiro described how McCarthy also had a heroin addiction, which began in his mid-20s.

He claimed it was Rachelle Bond, not McCarthy, who was obsessed with demons and the supernatural.

“Rochelle was projecting her delusions onto Michael, and she blamed him for what she in fact did,” Shapiro said.

He criticized her deal with prosecutors, which would allow her to walk free at the end of the trial based on time served.

Shapiro said there’s “nothing that will support the claim that Michael was obsessed with demons. He lived in the real world.”

He read excerpts from Rachelle’s journal to jurors, in which he said she detailed her beliefs about demons and children.

Bella Bond’s biological father, Joe Amoroso, was present in the courtroom Tuesday morning. According to prosecutors, Amoroso and Rachelle Bond met at the Occupy Boston camp in 2011.

Amoroso claims to have never seen his daughter while she was alive. Prosecutors said that when he came to Boston expecting to see his daughter, Rachelle told him she wasn’t there–and that he assumed the state had taken her.

Joe Amoroso, the biological father of Bella Bond, in court Tuesday. (WBZ-TV)

“I’m going to be here everyday because it’s all about justice,” Amoroso told WBZ NewsRadio 1030 last week. “I want to see them get their punishment.”

Before opening statements, the judge ordered the sequestration of Amoroso and other witnesses, including McCarthy’s father and brother, because they are expected to testify later in the case.

The trial is expected to take several weeks.

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