A 32-year-old woman has pleaded guilty to first-degree murder for torturing and killing a 17-month-old Staten Island boy she had been babysitting two years ago, authorities said Monday. 

Gloria Fields, who had initially pleaded not guilty in the February 2016 death of Anthony Delgado, changed that plea to guilty in Staten Island Supreme Court Monday and faces up to life in prison when she is sentenced later this month. 

Authorities say the boy's mother left him with Fields, a neighbor, for the weekend starting Friday, Feb. 19, 2016. Two days later, Fields texted the boy's mother saying he fell. When she brought him home, he was bruised and unconscious. An autopsy showed he died of blunt force injuries. 

Prosecutors had said Fields systematically tortured little Delgado, slamming his head on the ground while he was strapped in a stroller, shaking him and sexually abusing him with a pencil -- so much so that he had lacerations to his anus and perforated internal organs. Injuries covered all of the boy's body with the exception of his feet, prosecutors said.

“This defendant tortured and killed a 17-month-old boy who was left under her care, showing a cruel and inhuman disregard for life. Her guilty plea to first-degree murder ensures that she stays behind bars for her sickening crimes and is never allowed to do harm to another innocent child,” Staten Island District Attorney Michael E. McMahon said in a statement. “No family should ever have to experience the loss of a child in this way, and the entire DA’s office continues to send our thoughts and prayers to the family of the victim.”