Investigators are looking at persons of interest in the unsolved murder of Tracy A. Martin, whose body was found a month ago on the banks of the Collins River off Red Road.Still refusing to reveal the exact cause of death of the 38-year-old victim whose body was found by fishermen just before Thanksgiving last month, Sheriff Jackie Matheny said investigators are looking at and questioning persons of interest and he is hopeful that will lead to the case being solved and the murderer or murderers prosecuted. The sheriff has refused to confirm or deny the victim, who was found partially in the water and partially on the bank, suffered blunt force trauma and/ or gunshot wounds. Polygraph tests have also been conducted in connection with the investigation.“Sometimes cases can take a while and this is one of those cases,” Matheny said.