YAKIMA, Wash. (KIMA) — A Washington state woman has been arrested and charged with the strangulation of her 4-year-old stepson.

According to a press release from The Yakima Police Department, on Jan. 12, officers responded to an area hospital around 11 p.m. after staff called 911 to report there was an unresponsive child on the way to them.

The 4-year-old boy arrived at the hospital with no pulse and was not breathing. Doctors and nurses performed CPR on the child for 30 minutes before the child was pronounced dead.

Authorities say a police officer who responded to the hospital noted several large bruises on the boy’s body. The boy’s 25-year-old stepmother also made statements that raised suspicion, authorities said.

Detectives from the Yakima Police Department’s Special Assault Unit were called to the hospital to continue the investigation. During their interview with the stepmother, she admitted to strangling the child at their residence in the 1100 block of McKinley Avenue.

The stepmother was booked into the Yakima County Jail on a charge of seconnd-degree murder.

“At this point, the boy’s father, who was at work at the time of the incident, is not a suspect in the homicide,” Yakima Police Captain Jay Seely said. “This is such a tragic end to this young child’s life."

Yakima police are not releasing the name of the stepmother until she appears at a preliminary hearing in Yakima County Superior Court, which was expected to take place Friday.

An autopsy has yet to be scheduled.