The Bronx mom accused of murdering her two young sons was obsessed with demonic possession — and cops are investigating whether she killed the kids because she believed they were possessed.

“She made statements about the devil — unusual statements,” a police source told The Post of 22-year-old suspect Dimone Fleming.

Fleming chillingly wrote on her Facebook page Saturday before the slayings, “It’s only one true God and I repent from all wrong doings and negative influence.

“Leaving all things that no longer serves me…… Thank you for your mercy,” the woman added.

Fleming has been arrested but is now under psychiatric evaluation and awaiting charges in the grisly slaying of her 3-year-old son DeShawn Fleming and baby, Octavius Canada, 11 months, at the family’s apartment in a city homeless shelter, police sources said.

The boys’ bodies were found under a pile of wet clothes in the bathtub, their necks and torsos brutally slashed.

“[There’s] nothing, nothing in her history that would be indicative” of the horrific violence, a high-ranking NYPD source said Sunday, referring to the mom.

A neighbor said he confronted a crazed-looking Fleming outside the Echo Place building Saturday as she repeated, “What I did?!”

Cops who were then called to the address for a domestic disturbance arrived at 7:20 p.m. and found Fleming naked in the kitchen of her apartment trying to start a fire.

The officers didn’t notice that the two slain siblings were buried under a pile of clothing in the bathtub when they took the mom away. Officers had been told by a neighbor that the kids’ dad had them.

Fleming was taken to St. Barnabas Hospital for psychiatric examination.

But police were dispatched back to the shelter around 8 p.m. after a frantic 911 call from the boys’ dad, Columbus Canada, 31 — who found his kids dead in the tub.

Neighbors and acquaintances said the family had lived at the shelter for about a year — and said Fleming had been spotted behaving bizarrely and mistreating the children.

“She never had patience,” claimed Michelle Rivera, a mom and childcare worker who said she knows the slain siblings’ father.

“You’re only [22] years old, and you can’t deal with your children?” she said of Fleming.

“Everyone offered their help on this block to these kids with her, and she never took the help,” Rivera said. “She always wanted to pick an argument.”

She said Fleming would lash out at the children, yelling, “Here’s your f–king bottle!”

One neighbor said the 11-month-old was nicknamed “Baby O” by locals and added that she knew the children from nearby Echo Park, where they frequently played.

“The baby was really quiet,” the woman said. “DeShawn was the life of the park. He was just a happy kid.”