Police were looking for a suspect who knocked out a 31-year-old man and took his gold chain Thursday in Waipahu.

The victim told police he couldn’t recall what happened, but said he was missing a gold chain from around his neck.

Police said a witness saw the victim unconscious on the ground in the parking lot fronting Lee Town Center, 94-216 Farrington Highway, and saw the robber take the man’s gold chain and ran away about 11:35 a.m. Police searched the area, but couldn’t find the robber.

The man was described as 5 feet 5 inches tall, about 165 pounds, with black hair. He was wearing a black T-shirt and dark parts. A second-degree robbery case has been opened.