Saybra Martin (Jasper County Sheriff's Office).

A Missouri woman kept her 4-year-old stepson "confined" to a closet that reeked of urine and had flies "buzzing around" inside as a way to punish him, cops say.

Saybra A. Martin, born in 1996, is charged with abuse or neglect of a child in connection with the alleged confinement, which went on at her home in Carthage.

Deputies were called to the residence on Saturday, Aug. 15, after a Jasper County Children's Division worker with the Missouri Department of Social Services allegedly found the victim in the closet during a child abuse investigation.

An arrest affidavit filed Monday says Martin's stepson was "confined inside a closet" for approximately three hours "because of behavioral issues" and for "hitting his siblings." Martin also allegedly "spanked him on his buttocks using both her hand and a light brown paddle."

The boy told police he had been spanked "while wearing clothing" and on his "bare buttocks," according to the affidavit. He also said that Martin threw a Gatorade bottle at him, striking him in the head.

"The victim stated he cried after being struck, and Martin later gave him an ice pack," the affidavit says.

Deputies observed an empty Gatorade bottle on the floor of the closet where the boy was allegedly confined, along with a plastic Ziploc bag containing water, which was suspected to be melted ice, per the affidavit. They said the closet reeked of urine and there was a portable toilet inside, along with couch cushions.

"Significant bruising" was found on the boy's face and buttocks, according to police. "The bruising on the victim's face was consistent with someone forcefully grabbing his face," the affidavit says.

Martin allegedly admitted during an interview with police that she spanked her stepson but claimed she only struck him four times. She also confessed to throwing the Gatorade bottle at him and grabbing the boy by his face "to make him look at her while she was talking to him," according to the affidavit.

"Martin acknowledged that her actions were wrong and admitted that confining the victim in the closet was wrong," police say.

Three other children, in addition to the victim, were in Martin's home when cops were called to investigate. They are identified in the affidavit as a 10-year-old female, a 3-year-old male, and an 11-month-old female.

Investigators found trash piled up "both inside and outside the home," according to the affidavit. Police say that in the kitchen, they "observed cockroach activity and spoiled food on the floor."

The children inside Martin's home, including the victim, were all immediately removed over safety concerns. She has pleaded not guilty and is scheduled to appear in court on Aug. 26 for a bond review hearing.