The parents of an Arizona toddler who the authorities said was found breathing in a hospital morgue hours after being declared dead will not face charges, the Maricopa County Attorney’s Office announced on Wednesday.

On Feb. 8, the child, an 18-month-old boy, was found unresponsive in a backyard swimming pool. In a statement on Wednesday, the prosecutors said they were declining to charge the parents saying “the family had multiple childproof locks and safety measures in place, and multiple adults were present in the home, all of whom believed someone was watching the child.”

“After a review of the facts of the case and all available evidence by senior attorneys, it was determined that this case did not meet our charging standard of ‘reasonable likelihood of conviction,’” the statement added.

The parents could not be immediately reached for comment.

An employee of the medical examiner’s office in Maricopa County, who was sent to retrieve the body, discovered that the boy was alive, nearly five hours after doctors had declared him dead, and notified medical staff.

Police officers and firefighters arrived to the family’s home in Gilbert, a suburb southeast of Phoenix, at 5:35 p.m. that day after a report that the child had been found unconscious in a backyard swimming pool. Emergency medical workers performed CPR before taking him to Dignity Health Mercy Gilbert Medical Center, where doctors continued efforts to save his life. They pronounced him dead at 6:20 p.m., the authorities said.

Just before 11:30 p.m. that same night, hospital officials contacted police to report that the boy, whose body was to be transported to the medical examiner’s office, was breathing. He was transferred to Phoenix Children’s Hospital for additional treatment.

The discovery prompted the Gilbert Police Department to investigate both the circumstances of the drowning and the medical response that followed.

The parents told investigators that they had smoked marijuana that morning, according to a Gilbert Police report obtained through a public records request. Detectives also found that doors leading to the backyard had been left unsecured, creating what the report described as a “problematic and dangerous situation” that allowed the young children in the home access to the swimming pool, the report said.

“Detectives were able to smell an odor of burnt marijuana inside the garage,” the report said.

Police later recommended that prosecutors file child abuse charges against the parents. Prosecutors said their investigation “found no evidence that the parents exhibited any obvious signs of impairment.”

In a statement, Dignity Health Mercy Gilbert Medical Center called the episode “a heartbreaking situation” and said it had conducted a thorough review of the care provided “to learn what happened and to make meaningful changes to strengthen our care.”

The hospital declined to discuss which staff members were involved, or to elaborate on the circumstances of the case, citing patient privacy. But it said in the statement that it continues to work with the family and its representative.