Monique Osuna.

An Idaho woman pleaded guilty on Wednesday to first-degree murder for killing her stepson through a prolific and varied pattern of abuse.

It was supposed to be a new life for Emrik Osuna, 9, back in February 2018 when he moved in with stepmother Monique Osuna, 29, and biological father Erik Emmanuel Osuna, 31. His birth mother Sacil Siglaly Lucero had been locked up in California, charged with beating and badly injuring his fraternal twin siblings.

But authorities say Monique deprived Emrik of food and water, struck him with items including a belt, frying pan and dog leash, and forced him to sleep in a closet, according to a KTVB report. She forced him to exercise for sessions that could last for more than 12, even 20 hours.

“Each day, I would say over 12 hours a day, or thereabouts,” Meridian police Detective Matthew Ferronato previously testified. “Sometimes it would go on, 20-plus hours of constant exercise.”

This strenuous activity included jumping jacks and wall-sits. This even involved inchworms, in which Emrik had to walk on his hands from standing into a plank position, back to standing, and putting his arms up.

Nanny cam footage showed her kicking the child across the room, yanking him off the floor by his hair, and threatening to make him eat his own feces, officials said. According to investigators, Monique abused the child more often than Erik did. The father allegedly failed to step in as she tortured the boy.

Monique Osuna got mad that the 9-year-old drank a glass of water intended for another person, Ferronato previously testified. She refused him access to the bathroom when he asked.

Footage played in court showed Emrik’s ribs protruding.

Body of 9-year-old Emrik Osuna returned to OC and laid to rest as his father and stepmother remain jailed on charges related to his abuse and death https://t.co/uBkFINwKBq

— ABC7 Eyewitness News (@ABC7) September 24, 2020

There is a vigil to honor the life of 9-year-old Emrik Osuna tonight at 7pm in Caldwell. Everyone is invited to remember this precious boy. https://t.co/mchnLYtMnl pic.twitter.com/M8TMG9WCUe

— Maggie O’Mara (@maggieKTVB7) September 4, 2020

As part of her plea deal, Osuna admitted striking him with a metal spoon, her hands, and a frying pan to force him to keep exercising, according to The Idaho Statesman. She described Emrik as a “a sweet little boy that fit in really well with our family,” but he began showing “concerning behaviors,” according to KTVB.

“Unfortunately, my discipline of him escalated,” she wrote. “Before I knew it, I was abusing him, and that abuse killed him.”

Erik Emmanuel Osuna.

Emrik died in September 2020. Cops in Medirian, Idaho, went to his home because he was not breathing. Cops could not detect a heartbeat. Officers reported finding signs of abuse. Emrik passed away the next day at St. Luke’s Regional Medical Center.

Monique Osuna’s sentencing is set for June 9. In exchange for her plea, prosecutors will not seek the death penalty. Charges against the father are pending.

Emrik’s biological mother Lucero pleaded guilty in California and was sentenced to four years in prison or time served for beating her 15-month-old fraternal twins, knocking out the daughter by bashing her head against a bed pole, according to NBC Los Angeles. She said that she jealous the twins’ father paid more attention to them than her, cops said. Police said the girl sustained a brain bleed, and that doctors also discovered a broken elbow, which had been healing. Her brother had a skull fracture and broken ribs, authorities said.

[Booking photos via Ada County Sheriff’s Office]

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