FORWARD TWP — It's been a month since someone fired a fatal shot into Robert C. “Bob” Gaurrich's chest at his auto repair shop. State police are still searching for the shooter. They apparently know little more about him — or her — than what they had learned in the initial investigation. No suspects have been identified, Sgt. Patrick Sarnese admitted last week. Elusive clues and unanswered questions deepen the mystery and frustrate investigators. “This case is difficult,” Sarnese said, “because there's an unclear motive and because there are many people that could be involved.” But if the homicide investigation is stalled, Sarnese is not saying. Interviews go on and forensic testing of evidence continues. However, he conceded police are waiting for the lead that's going to break open the case. The 45-year-old Gaurrich was found dead about 11 p.m. Jan. 11 behind Bob's Truck and Auto Repair Service, a business he operated on Route 68 for several years. An autopsy revealed he died of a gunshot wound to the upper chest. Police recovered a .30-30 caliber shell casing near a door to the garage. A blood trail led from that door to Gaurrich's body. Investigators say he was shot, possibly as early as 4 p.m. that day, inside his business and died outside. Since the start of the case, police have been seeking what could be the most important piece of their puzzle — the .30-30 rifle that Gaurrich kept at his shop. That rifle, police acknowledge, could turn out to be the murder weapon. A short time before his death, Gaurrich was trying to sell that same rifle, Sarnese said. Police have also theorized that because there was no evidence of forced entry at the business and because Gaurrich did not appear to have any defensive-type wounds, he may have known his killer. Police have already conducted more than 50 interviews as part of their probe. Family members, friends and associates have been brought into the barracks and questioned. Immediately after the killing was discovered, investigators for hours spoke to Gaurrich's live-in girlfriend, Jessica L. Hoover, and her former boyfriend, Bradley McCool. Hoover called McCool that night for help when she couldn't find Gaurrich at his shop. Police said McCool reportedly came upon the body face down in a pile of stones. Hoover and McCool have been cooperative with investigators, Sarnese said. Police acknowledged they have used polygraphs during their investigation. While polygraph exams are not admissible in court, police and prosecutors regard them as a valuable investigatory tool. Polygraphs, Sarnese said, are used “to aid us in proving or disproving” information from suspects or potential suspects. Police, meanwhile, have not unraveled the time line of Gaurrich's slaying. Investigators are uncertain about who the last known person was to see him alive. “People were in and out of that building all day,” Sarnese said. “Reports have been scattered.” The last known person to speak to Gaurrich apparently remains a mystery, too. Police believe Gaurrich made his last phone call at 3:50 p.m. Jan. 11, leaving an innocuous message for Hoover. Asked if the victim had any enemies, Sarnese said he did not know. “He had disagreements with people, like any other person,” Sarnese said. But police have no reason to believe those differences could have motivated someone to want to kill Gaurrich. A financial motive in the killing has apparently not been ruled out. Police have acknowledged that Gaurrich's business had seemingly dropped off in the past year to two before his death. Sarnese would not say if Gaurrich owed anyone money.