A 31-year-old man is in custody in connection with a manslaughter investigation involving the death of his 61-year-old father in Waipahu.

A family member has identified the victim as Nelson D. Corpuz of Waipahu.

Police said a suspect, identified as Lanch Corpuz, was involved in an argument with his father, later identified as Nelson Corpuz, at a residence at about 4:15 p.m. Monday when the dispute escalated and Lanch Corpuz punched Nelson Corpuz.

Police did not disclose the reason for the argument.

Nelson Corpuz was taken in critical condition to a hospital where he died Tuesday morning.

Lt. Deena Thoemmes of the Honolulu Police Department’s Homicide Detail said preliminary autopsy findings indicate Nelson Corpuz died of “blunt force head injury.” His death has been classified as a homicide.

Police initially arrested Lanch Corpuz at the residence on suspicion of second-degree assault. The case was reclassified to manslaughter after his father died. Lanch Corpuz was later charged with manslaughter and was given a $20,000 bail.

Nelson Corpuz, originally from Laoag City of Illocos Norte, Philippines, was a retired welder with a business called NDC Improvement and Repair Services LLC.

Prior to working as a welder, Nelson Corpuz worked in the maintenance department of the Outrigger Waikiki Beach Resort for 20 years, said his wife, Esther Corpuz. He was a hard-working man, she said.