BOSTON (CBS) – The man accused of killing two-year-old Bella Bond claimed in an interview with police that he didn’t know the little girl was dead.

Michael McCarthy, 37, is facing a first-degree murder charge in two-year-old Bella’s death.

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Michael McCarthy in court Thursday. (WBZ-TV)

Massachusetts State Police Trooper Joel Balducci interviewed McCarthy in September 2015.

On Thursday afternoon, jurors listened to that interview, in which McCarthy told Trooper Balducci that the girl’s mother, Rachelle Bond, told him “DSS” had taken Bella.

McCarthy could be heard in the interview saying he was surprised about that, because he thought Rachelle was a “good mother.”

But Balducci told McCarthy in that interview that Rachelle told police a different story.

McCarthy then claimed not to even know the little girl was dead.

“She’s dead? … not to my knowledge,” McCarthy said in that interview.

Prosecutors say McCarthy struck and killed her because he was obsessed with the occult and believed she was a “demon.”

The defense, however, claims the girl’s mother, Rachelle Bond, killed her daughter.

Bella Bond. (Photo credit: Facebook photo)

Testimony began Thursday with a State Police trooper who specializes in cell phone tracking technology. He described to the court where McCarthy and Rachelle Bond’s cell phones were pinged before, during, and after Bella’s murder.

Trooper Sgt. David Crouse said the exact location in South Boston the day after Bella’s body was discovered is unclear, despite the pings caught by towers. He likened the precision of the technology to a game of catch with Tom Brady.

“Tom Brady is kind of like the tower–great arm,” he said. “I don’t have a great arm. Tom Brady can throw the ball to me 80 yards away. I’m the cell phone. If I want to throw to him, I have to get close to that tower to be able to throw it to Tom.”

Next, a State Police diver testified about finding weights and a military-style duffel bag that Bond claims Bella’s body was dumped with.

Former trooper Scott Mackenzie identified the duffel bag and weights in photos shown to the court, which he said were taken before he picked the items up and gave them to police on shore.

He said he found the items 9 feet down, after about five minutes of searching.

A photo shown in court of the weights used to dump Bella Bond’s body in Boston Harbor. (WBZ-TV)

On Wednesday, a series of crime lab scientists testified and showed there was no blood, DNA, or fingerprint evidence on either those items found by the diver or Bella’s body that tied McCarthy to the crime.

On cross-examination, Mackenzie said there was no way to know who put the items there, or how long they had been there. Defense attorney Jonathan Shapiro said that wasn’t enough to point to McCarthy.

Bella’s body washed up on a Deer Island beach in July of 2015. Bella was known as Baby Doe as she went unidentified for months. Police said the digitally-generated photo of the toddler had been viewed on the internet more than 50 million times.

Trooper David Swan testified that he determined the leggings found on the child’s body were purchased from Target. He used store records to track down and knock on the doors of about 100 people who bought them.

He said that if the person who answered the door was able to produce those leggings, he knew they were not involved in Bella’s murder–but he said none of those door knocks led him to Bond or McCarthy.

Trooper Swan also showed searches from McCarthy’s phone–including “satanic human sacrifice” and searches about demons.

The case against McCarthy will depend on whether or not the court believes the account of Bella’s death told by Rachelle Bond during her testimony.

As part of a plea deal with prosecutors, Rachelle could get a reduced sentence as an accessory after the fact of murder and walk free on time served at the end of the trial–if McCarthy is found guilty.

If not, she could potentially be prosecuted for perjury–and potentially face life in prison–if the jury decides they don’t believe her account of Bella’s death.

Judge Janet Sanders is now considering whether or not to grant the prosecution’s request to add a manslaughter charge to the list of possible charges for McCarthy, in case the murder charge doesn’t stick. The defense objected to that request.

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The prosecution is expected to rest Thursday or Friday, and the jury is expected to get the case next week.