A missing mom whose rotting body was found buried in a shallow grave on a Queens beach over the weekend was shot repeatedly – and investigators believe she may have known her killer, cops and sources said Monday.

Seraphina Pereira, 35, was last seen around 11 a.m. last Monday leaving her Beach 54th Street home — about a half-mile from Rockaway Community Park in Edgemere, where her body was found wrapped in a blanket in a shallow hole five days later, police said.

Her remains were already decomposing in the pit when police descended on the scene around 9:45 p.m. Saturday, law-enforcement sources added.

Pereira had suffered gunshot wounds to the head, neck and torso, and her death was ruled a homicide, according to the city medical examiner’s office.

The Queens mom frequently posted about her children on Facebook — most recently sharing a 5th birthday post for her son, just days before her disappearance.

About a week earlier, she shared a selfie with her "lil diva" daughter, who she said did her make-up, as both posed in green eye shadow.

A person of interest was taken into custody Monday evening, police announced.

However, no charges had been filed by Monday night.