The family had a home security system and kept close watch on their six children. Valva's three sons ages, 6, 8 and 10, and Pollina's three daughters ages, a 6-year-old and twin 11-year-olds, WNBC reported.
Footage showed Valva routinely withheld food as a punishment and exposed his sons to cold temperatures, investigators said.
"We are still investigating the extent of the abuse and if it extended to all of the children," Hart told WNBC.
Michael Valva and Pollina were arrested and charged with second-degree murder, officials said.
Valva, who joined the NYPD in 2005, was suspended, the Times reported.
The attorney for Valva and Pollini maintain their innocence, WNBC reported.
The couple will be arraigned Saturday.
Shortly after his son's death, Valva raised $16,000 on a GoFundMe account to pay for the boy's funeral, News 12 Long Island reported.
The boy's mother, Justyna Valva, lost custody of the boys, the Times reported. She had not seen Thomas in two years until looking at his body in the medical examiner's office.
"I just really want justice for my son," she told WNBC. "He deserves it. This should never have happened."