A Texas mother confessed to killing her 4-year-old son was arrested on Monday, and police say the grandmother watched as the child was killed.

Henderson County Sheriff Botie Hillhouse said that Monica Figueroa, 42, was arrested on Monday after she allegedly killed her son, Grayson Hurt, on Sunday with an "edged weapon," according to CBS 19.

According to the report, Mary Johnson, Figueroa's mother, called police and was worried that her daughter had hurt the 4-year-old. 

When officers got to the house, they found Hurt deceased and partially covered by a blanket. Figueroa was located at the home and taken into custody.

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Texas jail

Monica Figueroa (L) and Mary Johnson (R) (Henderson County Jail)

Hillhouse said that Johnson observed her daughter on top of a rolled blanket while cutting it with a wooden handled knife, saying that she heard screaming.

"Johnson heard the child screaming before she observed Figueroa cutting at the blanket and then the screaming stopped," Hillhouse said. "Figueroa threatened Johnson and instructed her to leave which she did."

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Johnson came back to the house on Monday morning and saw that Hurt was dead, prompting her to call 911.

When investigators began questioning Figueroa, she allegedly admitted to killing her son.

Hillhouse said that Figueroa had one child in the home, adding that she doesn't have custody of other children belonging to her.

Figueroa was arrested under a charge of capital murder of a person under 10-years-old and Johnson was also arrested and charged with endangering a child.

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Hunt's body was sent to Dallas for an autopsy.