A 3-year-old boy who police say was fatally assaulted was found not breathing in his stepfather’s Grand Prairie apartment, according to an arrest warrant affidavit.

The child, Zyair Amerson, was taken by family members on the morning of May 11 to an emergency room at Arlington Memorial Hospital for injuries consistent with assault. The boy was later transported to Cook Children’s Medical Center in Fort Worth due to the severity of his injuries, and was pronounced dead by medical staff on May 15.

The boy’s stepfather, 21-year-old Solnifasint Nelson, was arrested on May 11 on a charge of injury to a child causing serious bodily injury or death, a first-degree felony.

The family told Grand Prairie police that Nelson put Zyair to sleep on the evening of May 10 but when they tried waking him up in the morning, he was not responding and was not breathing, according to the warrant.

In an interview with police, Nelson said he fed his children that evening and put them to bed at around midnight with no issues. The warrant says Nelson was not cooperative with officers who responded to the scene and he would not tell them which apartment he lived in.

When police responded to the hospital, Nelson then admitted to officers that he spanked Zyair with a belt about four days prior and that it left a bruise on his back, but he said he did not notice any issues with the 3-year-old the day before he was hospitalized, according to the warrant.

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Police said Nelson’s account did not match the child’s medical findings or the witness testimonies from other people who were at the apartment.

Nelson then changed his story, the warrant states, before ultimately telling detectives the boy fell on the living room floor. He told police he did not know how the fall occurred because he was in the kitchen at the time. Zyair cried after the fall and Nelson put him to bed, according to the warrant.

Zyair continued to sleep for the rest of the day and Nelson did not assume anything was wrong until the child was found not breathing the next morning, the stepfather told police.

Even after being told his account did not match other testimony, Nelson insisted his account was true and said he did not know why anyone would say different, the warrant states.

The Tarrant County Medical Examiner’s Office has not yet ruled on the manner or cause of Zyair’s death.

On a GoFundMe page organized for the 3-year-old, family members allege he was a victim of shaken baby syndrome and brain death caused by an adult caring for him while his mother was working.

The fundraiser, which has raised over $1,600 out of a $10,000 goal, asks for donations to go toward funeral and memorial services.

Nelson is in the Tarrant County Jail with bond set at $250,000.