'What The (Expletive) Did You Do?': Mother Testifies Against Bella Bond's Accused Killer

BOSTON (CBS) - The prosecution's star witness took the stand Friday in the trial of Michael McCarthy, the man accused of killing 2-year-old Bella Bond.

Bella's mother, Rachelle Bond, began to testify against McCarthy, her ex-boyfriend, claiming he killed her daughter in 2015.

McCarthy, 37, is charged with first-degree murder in Bella's death. Prosecutors say he struck and killed her because he was obsessed with the occult and believed she was a "demon."

The defense, however, claims Rachelle Bond killed her daughter.

As her testimony began, Rachelle Bond said she began smoking marijuana before she turned 18, used cocaine several years later, and by age 24 was smoking crack cocaine.

She also admitted in court that she has a history of prostitution, and lost custody of two children due to neglect.

Rachelle Bond admitted to having a past criminal history and told the jury that she is testifying against McCarthy after pleading guilty to accessory after the fact for covering up Bella's death.

Bond recalled how she met McCarthy, and said that he seemed like a "nice person." She said McCarthy came over to her apartment to share drugs in February 2015, and never left.

Though Bond said McCarthy was good to Bella, she added that "He said you need to discipline her more...you need to stop picking her up."

At one point, she said McCarthy locked Bella in the closet because she was "being fresh."

When asked what day Bella died, Rachelle said she didn't recall the exact date. She said it was 11 p.m. or later, and Bella didn't want to go to sleep.

McCarthy went into her room, Bond testified, while she watched a movie.

Bond added that when she came back in the girl's bedroom to see if McCarthy needed help, the light was on and she saw him punch Bella in the stomach.

"What the (expletive) did you do?" Bond says she yelled to McCarthy.

Through tears, Bond testified that she attempted CPR on Bella. But she said McCarthy grabbed her by the throat and threatened to kill her.

Bond said that when woke up after McCarthy injected her with heroin, they were near Boston Harbor.

The day after McCarthy disposed of Bella's body in the Boston Harbor, Bond testified that she asked what he had done.

According to Bond, McCarthy said Bella was a demon and it was "her time to die."

Before Rachelle Bond took the stand, the cross examination of McCarthy's friend, Michael Sprinsky, wrapped up and McCarthy's older brother Joseph also testified.

Sprinsky testified Friday that Michael McCarthy was "deep into the dark side of things."

When asked if McCarthy ever told him that Bella was possessed by demons, Sprinsky replied "All the time."

Joseph McCarthy said Michael began struggling with drug addiction at 17 years old, first taking pills then switching to heroin.

Prosecutors questioned Joseph McCarthy about a weight bench in the office of his father's plumbing office, where Michael McCarthy previously stayed.

After Bella Bond was killed, her body was placed into a duffel bag with weights and thrown into the water.

Joseph McCarthy testified that after seeing Bella at family gatherings, he was told in July 2015 that she was not around because she was with her biological father for the summer. The statement came during the time Bella was missing.

During defense questioning, Joseph McCarthy said his brother's interest in demons was due to his Catholic upbringing. When asked if his brother believed Bella Bond was possessed by demons, Joseph McCarthy said no.

There was no testimony Thursday as jurors toured the spot where Bella's body washed ashore on Deer Island and other locations central to the case.