A 44-year-old homeless man died Tuesday afternoon after fighting with another man at Waimanalo Beach Park.

Homicide Lt. Deena Thoemmes said the victim and a 37-year-old man were involved in a fight at about 12:15 p.m., when the older man collapsed near the restrooms at the park.

He was taken to the Adventist Health Castle where he was pronounced dead an hour or so later, but police do not yet have a cause of death.

Police have opened a murder investigation in the case.

On Wednesday, police released the 37-year-old man pending investigation.

Thoemmes said the two men, who are “residentially challenged,” were reportedly involved in a fight over the suspect’s girlfriend. No weapons were used.

Responding officers arrested the 37-year-old at 12:34 p.m. Tuesday on suspicion of second-degree murder after the incident.

Two other men who also live at a homeless encampment at the edge of the park say that the suspect and victim also lived there. But Auntie Lavina Aina, the unofficial leader of the encampment, said Thursday the victim and suspect do not live there.

Billy, one of the camp’s residents who did not want his last name used, said the 44-year-old was talking after he collapsed so he was shocked to learn that the man died.

He estimated the victim was about 6 feet 1 inch tall and weighed 225 pounds, while the other man was small.

Billy said first responders were “performing CPR for a long time.”

He said he heard the fight was over a relationship. “It’s not worth it,” Billy said. “Innocent people lose their lives.”