NEW YORK (CNN) — A caretaker who allegedly inflicted “unimaginable pain” in the final weeks of a 4-year-old boy’s life has been indicted on a murder charge in his death, prosecutors said Thursday.

The second-degree murder indictment against Kryzie King, 27, comes five months after she allegedly beat and tortured little Myls Dobson while the boy was in her care in a Manhattan apartment, prosecutors said. She pleaded not guilty during an arraignment Thursday, according to District Attorney Cyrus Vance.

The murder charge was added after the medical examiner’s office concluded in April that Myls died from “child abuse syndrome including dehydration,” said Julie Bolcer, spokeswoman for the New York City medical examiner’s office. The manner of death was homicide.

“Myls Dobson was forced to suffer unimaginable pain in the last weeks of his short life,” Vance said in a statement.

Bryan Konoski, King’s attorney, did not return a call seeking comment.

According to the indictment, King “repeatedly assaulted (Dobson), including binding his hands and feet, striking him with an electrical cord and belt buckle, locking him outside on a patio in record low temperatures, and burning him with a hot oven rack.”

Myls died January 8 after his father, Okee Wade, left the boy in King’s care before Wade went to jail in connection with a fraud case, police said.

King told investigators she starved, beat and burned the boy before his death, according to a criminal complaint.

On the day Myls died, King called 911 after allegedly assaulting him. When police arrived, they found Myls unconscious and unresponsive on the floor of a bathroom at King’s apartment at the Ritz Plaza, a luxury high-rise in the Hell’s Kitchen section of Manhattan.

Myls was later pronounced dead at St. Luke’s Hospital.

In January, Assistant District Attorney Nicole Blumberg told the court that Myls was a happy, healthy, well-nourished little boy when he arrived at King’s home in mid-December 2013. But when police found Myls in her apartment, the prosecutor said, his body was burned, bruised and cut from head to toe.

In addition to second-degree murder, King is also charged with assault in the first degree, attempted assault in the first degree and assault in the second degree.

King was remanded until her next court hearing scheduled for September 17.

A review of the case later found that New York City child welfare caseworkers visited the boy’s home nine times without even realizing that his father was in jail, city officials said.

Wade, 37, who has an extensive criminal record, was awarded custody of his son in August 2012 on the condition that the city’s Administration for Children’s Services check up on the child for a year and contact the father’s parole officer.

Caseworkers, however, never consulted the parole officer and never learned that Wade was jailed during their visits to the Brooklyn apartment where he was staying with his son, according to a review of the case ordered by Mayor Bill de Blasio. His partner at the time told caseworkers that he was working. At the time, Myls was staying with King.

De Blasio ordered a review of all cases involving court-ordered supervision at the agency and said custodians must now get a family court judge’s approval before supervision ends.