But first tracking down a killer in a growing murder mystery, the shocking Christmas eve double shooting first made headlines when a woman and her fiance's brother were killed in a parking lot. Then a... See More
But first tracking down a killer in a growing murder mystery, the shocking Christmas eve double shooting first made headlines when a woman and her fiance's brother were killed in a parking lot. Then a third body was found after that. The woman's fiance. Now people releasing details of the man they are looking for. Reporter: It's a puzzling story. Police have been trying to figure out for weeks what led to a double murder in a mall parking lot on Christmas eve. And now they have critical new information to help them crack the case. This morning, San Diego police have confirmed the body found in the trunk of a car on January 17th in a fast food parking lot is that of 24-year-old Gianni belvedere -- The preliminary autopsy results have shown his manner of death is homicide. Reporter: Employees working nearby had noticed an odd smell coming from the car. One of my co-workers parked two cars down and could smell it. Reporter: It's 100 miles away from where his brother and fiance were killed. New information in a case that continues to baffle investigators. Police say belvedere went missing Christmas eve, the same night his brother Salvatore and Gianni's fiancee Ilona Flint were found shot in the head in this mall parking lot. We're going to have two victims. Reporter: For weeks they searched for Gianni not named a suspect but was considered a missing person at risk. At first authorities believed a love triangle could be a possible motive. But now police say they are on the hunt for a killer on the loose. The person of interest that we are looking for is an unknown race male, 5'10" to 6 feet tall. The belvedere family seen here at a press conference. We love you and miss you very much. Reporter: Is offering a $10,000 reward to capture and convict the suspect or suspects involved. Hoping it will help police un-ralph this murder mystery. It's hard to fathom where this goes. But this, they were killed because of some revenge or some payoff or some version of that. Police say they still don't know how Gianni belvedere was killed. They're waiting for the full autopsy report. That's expected to come out in just a few weeks. Dan and bianna. Still so many unanswered questions. Yeah. Ron, you got an update for us?
This transcript has been automatically generated and may not be 100% accurate.