A 4-year-old boy died Sunday night after allegedly being severely beaten last week by his mother's boyfriend, who now faces murder charges, a Long Beach police spokesman said Monday.
Kenneth Ogasawara was visiting his mother, Misumi Ogasawara, 22, who was living with Steven Bertini, 25, at their residence in Long Beach, Calif.
The child and his 48-year-old grandmother, who live in the city of Kagoshima, had been in California for about a month for a family visit when the boy was beaten. The two were scheduled to return to Japan last Friday.
Early that morning, paramedics responded to an emergency call and found the boy unconscious and suffering from severe head trauma and other serious injuries.
The child was later operated on at a local hospital.
Authorities investigating the incident arrested Bertini on Friday on suspicion of attempted murder.
So far, the boy's mother and grandmother have not been charged with any crime.