An Indiana teen accused of smothering his two toddler siblings to death told authorities he did it to free them “from Satan and hell,” according to a new report.

Prosecutors say that Nickalas James Kedrowitz, now 15, suffocated his half-sister, 23-month-old Desiree McCartney, and his stepbrother, 11-month-old Nathaniel Ritz, in their Osgood home when he was only 13 years old, the Indianapolis Star reported Wednesday.

He was charged as an adult on Sept. 4, and his jury trial is set for Feb. 18, 2020, the Star reported.

Desiree was the teen’s first alleged victim. Stephen Ritz, who was engaged to Desiree’s mother at the time, told Nickalas to watch the tot as he checked on the other children on May 1, 2017, according to the report.

Nickalas then allegedly told Ritz that the little girl had stopped breathing.

The toddler’s mother, Christina McCartney, was just getting home and performed CPR, the outlet reported. The little girl was rushed to the hospital, where she was pronounced dead five days later. An autopsy was inconclusive.

On July 20 of that year, McCartney had asked Nickalas to take Nathaniel to bed, the paper reported. Moments later, the teen reported that the boy “ain’t moving.”

He was pronounced dead at the hospital the next morning.

Nathaniel’s autopsy, too, was inconclusive.

Nickalas was also accused of “mutilating a kitten to the point of almost killing it” about a month after Nathaniel’s death at his aunt and uncle’s home, according to court documents obtained by the paper.

He was angry at the animal because it had scratched him, and he allegedly squeezed it, the documents said.

His aunt and uncle decided to take the kitten outside to put an end to its suffering — and Nickalas asked if he could join to “see the kitten’s brains splatter everywhere,” the documents say.

During a psychological evaluation later that year, the teen spoke about “freeing his siblings from Satan and Hell,” as well as “large knives and burning fire,” according to additional documents obtained by the paper.

But he didn’t respond to a question about whether he was responsible for “freeing his siblings or causing their deaths.”

Nickalas later told police he’d spoken to God about Desiree and Nathaniel, and promised God he wouldn’t speak to anyone about it, according to the report.

But police ultimately got him talking — and the boy spoke about a dream in which he and an angel saved the toddlers “from hell and the chains of fire.”

He told authorities he never wanted to hurt the children, only to “set them free from this hell,” the paper reported. He admitted to placing a towel over Desiree’s head and a blanket over Nathaniel’s, court documents revealed.

“Hell,” for Nickalas, referred to his “chores,” the documents said.

In January 2018, amended autopsy reports listed both toddlers’ deaths as homicides, by asphyxia due to smothering, according to the report.