YAKIMA -- Bail was set at $1 million for an 18-year-old man suspected of beating a 2-year-old Sunnyside boy to death.

Juan Balverde Lopez made a preliminary appearance Friday in Yakima County Superior Court, where he is expected to be charged with second-degree murder in the death of Benjamin G. Miron.

The 2-year-old died of internal injuries caused by blows to his torso, authorities said.

According to court documents filed by prosecutors, Balverde Lopez told police he struck the child in the abdomen twice because he was tired and frustrated that the child had been getting up throughout the night.

The child had new and old cuts, bruises and scars on his face and body, according Yakima County Coroner Jack Hawkins. Balverde Lopez was unable to explain the injuries, according to charging documents.

Balverde Lopez was baby-sitting the child and his two siblings while their mother, Pia Grace Miron, 25, was at Toppenish Community Hospital, authorities said.

On Wednesday morning, Balverde Lopez found the child unresponsive and took him to the Toppenish hospital, police said.

Police said it's unclear whether he took the child there for emergency treatment or to visit the mother, who he was dating.

Sunnyside police believe the boy had been fatally beaten the night before. Police said family members told them they saw the boy about 7 p.m. the night prior to his death and do not remember seeing bruises on his face. Police said that Balverde Lopez was the only adult at the home that night.