A babysitter charged with murdering a 16-month-old boy whose family lived in the same Staten Island building subjected him to hours of physical and sexual abuse while he was left in her care over the weekend, prosecutors said on Wednesday.

The babysitter, Gloria Fields, made her first appearance in Criminal Court on Wednesday, where a prosecutor outlined accusations of torture that led to outbursts of sobbing and screaming from the child’s relatives and others packed into the courtroom.

Ms. Fields, 31, sexually assaulted the boy, Anthony Delgado, with a crayon, and while the toddler was strapped in a stroller, she slammed him face first into the ground, prosecutors said.

On Sunday night, when she took him to his uncle who lives upstairs, the boy was unconscious and unresponsive, and pronounced dead later that night. He had multiple skull fractures, internal bleeding, cuts and bruises to his face and across his body, as well as internal injuries caused by the sexual assault, according to prosecutors.