Maui County authorities have charged a 32-year-old Wailuku man and his 27-year-old live-in girlfriend with second-degree murder after the man’s 4-year-old son died of blunt-force trauma injuries, police said today.

Kyle McKeown and Grace Lee-Nakamoto remained in custody today on bail of $500,000 each.

Police said McKeown took his son to the emergency room of Maui Memorial Medical Center at 10:57 p.m. Tuesday after the boy was found unresponsive in the shower of their home, police said. The boy died at 4:33 a.m.

An examination by emergency room doctors showed the child had sustained severe blunt-force trauma to his internal organs and subsequently died, police said.

The McKeown and Lee-Nakamoto told officers they did not know how the boy was hurt, police said.