HONOLULU (KHON) – Honolulu police have confirmed they are investigating a homicide involving a 73-year-old victim and a 23-year-old suspect who authorities say were in an intimate relationship.

Police were sent to the home Monday morning on a report of a missing person.

“Yesterday we saw an officer right over there looking in the grass and investigating so we thought there was a robbery or something,” Sydney Holst, a resident living nearby, said.

Later in the afternoon, missing persons detectives returned to the scene where they met with a 23-year-old man who said he resided at the home and who was later confirmed to have had an intimate relationship with the missing person.

“It didn’t appear suspicious at that time,” Lt. Deena Thoemmes of HPD said. “Missing persons detectives [were] notified and responded to the scene to continue the investigation.”

During the investigation, a standalone tub was found filled with a concrete mix. A body, which Honolulu police believe to be the victim, was later located in a state of decomposition within the mix.

“The smell of the decomposition was when we started to chip away at the tub,” Thoemmes said.

The 23-year-old man left the residence with a 34-year-old man by the time the victim was found. Honolulu police have confirmed they are suspects in the case.

Both men were last seen on Tuesday at around 1 a.m.

Anyone who knows the whereabouts of the suspects is asked to call police or CrimeStoppers.

Honolulu Police have not released the name of the victim. According to Lt. Thoemmes, an autopsy will be conducted Wednesday to determine the cause of death.