What to Know An NYPD officer and his fiancee face charges in the death of his 8-year-old son at their Long Island home

At the time of little Thomas Valva's death last week, police were called to the Center Moriches residence for a fall in the driveway

Audio files from the home recorded the couple saying the child was hypothermic, couldn't walk and was "face-planting" on concrete

A veteran NYPD officer and his fiancee have been arrested in the mysterious Jan. 17 death of the cop's 8-year-old son, law enforcement sources familiar with the investigation told News 4 Friday.

The father, 40-year-old Michael Valva, and his fiancee, 42-year-old Angelina Pollina, are both charged with second-degree murder in the death of little Thomas Valva.

Michael Valva offered no explanation as he and Pollina were led to court Friday, where the pair pleaded not guilty. Valva was ordered held without bail.

"They evinced no regard for this child's human life," Suffolk County District Attorney Timothy Sini said after the arraignment. "They caused his death both by forcing him to sleep in frigid temperatures in the garage and then by failing to do anything to help him as he died right in front of their eyes."

Assistant District Attorney Laura Newcombe said during the arraignment of Valva and Pollina late Friday that audio files recovered from the home recorded the couple discussing the fact that the child was suffering from hypothermia, had been washed with cold water, couldn't walk and was "face-planting" on the concrete on the morning he was killed.

Newcombe said that a recording from Jan. 17, the morning of the Thomas Valva's death, began with another child asking: "Why can't Thomas walk?"

Newcombe said that Pollina answered "because he's hypothermic," adding, "When you're washed with cold water and it's freezing you get hypothermia."

Valva's voice then said, according to Newcombe: "He keeps face planting on the concrete."

Sini said he had listened to the audio himself. "I can't describe it in words," he said. "The depravity of these defendants is shocking."

Cops responding to the scene at his Center Moriches home last week initially were responding to reports of a boy who had fallen in the driveway. Suffolk County Police homicide detectives had been investigating his death since. According to police, by the time Thomas Valva got to a hospital his body temperature was only 76 degrees, possibly indicating an earlier time of death.

An autopsy was ordered to determine how he died. The medical examiner ruled the boy's death a homicide, finding found that hypothermia was a major contributing factor, Hart said.

Suffolk County police said at a Friday afternoon press conference that they believe Michael Valva's 8- and 10-year-old boys were subjected to extreme punishment. There is a third child in the family as well.

Investigators say they used video and audio from cameras inside the house to confirm a pattern of abuse against Thomas and an older brother — both diagnosed with autism.

A neighbor told News 4 that she once worked as a nanny in the family's home, and while they were verbally abusive, she "never thought it would end in somebody's death."

Thomas Valva's biological mother, Justyna, alleged a track record of "enormous abuse" by her ex-husband, with whom she has two other children. She said she at one point lost custody of all three kids, though didn't elaborate on the reasoning — and alleged her ex tortured the trio, starving and beating them and locking them in the garage for periods of time. Justyna Valva said the children would go to school soiled and wearing diapers, even though all had been potty trained by age 2.

They looked for food in the school garbage and on the floor, Justyna Valva said as she choked back tears, claiming "no one did anything" to help. Justyna Valva said she fought in the court system for five years to get justice for her children — and now her 8-year-old boy has lost his life.

She also said that the abuse was ignored when she lost custody during a bitter divorce battle. Suffolk Police say those claims are being investigated.

A statement from Suffolk County Department of Social Services Commissioner Frances Pierre read in part: " “The Department of Social Services is heartbroken by the passing of Thomas Valva. Department personnel are continuing to provide all available information on this matter to law enforcement and will continue to cooperate fully throughout the investigation."

The statement goes on to say that petitions for child neglect were filed in 2018 and that "safeguards ordered to protect the children included court-ordered home supervision for a period of one year, Orders of Protection for the parents to refrain from harmful behaviors towards the children and mandated participation in a Positive Parenting Program had been put in place."

However, subsequent additional complaints related to the Valva/Pollina family were investigated, according to Pierre, who also said in her statement that the department "is formally reviewing the management of the case to ensure that all protocols were followed in accordance with the law."

Suffolk County police said Friday Thomas Valva was held in the garage overnight — with temperatures dropping below 20 degrees — before his death. When cops arrived, his father, an NYPD officer, was performing CPR on him in the basement of the house. There was a previous report of a welfare check -- in May of last year, police said. When authorities arrived the family wasn't home; neighbors told police they were in Queens. Suffolk County cops didn't say if police ever followed up.

"I just really want justice for my son. He deserves it. This should never have happened," Justyna Valva said. "I just keep praying for this case to be fully resolved and my little angel Thomas to rest peacefully in heaven."

"I just wish I had more time with him on this Earth," she added. "I just wished somebody helped him."

The surviving children, whom Justyna Valva said she hadn't seen in about two years, are with her now. She said they're spending time catching up. She also works in law enforcement -- as a correction officer on Rikers Island.

Justyna Valva described her ex-husband as "extremely unpredictable" and said he had trouble controlling his anger.

He appeared to launch a GoFundMe page for burial expenses for his son shortly after he died. The page, posted earlier this week, raised more than $14,000 as of Friday morning to pay for funeral expenses for Thomas Valva.

"It is with great sadness that I must bury my 8 year old son. He passed recently due to a tragic accident," the organizer, who listed himself as "Michael Gerard," posted.

NYPD records list Michael Valva's full name as Michael G. Valva. He has 15 years with the department; he started in 2005 and is assigned to transit. The NYPD said he had been suspended without pay pending the outcome of the investigation.

No attorney information for him or his fiancee was immediately available.