TERRELL -- A Texas prosecutor gunned down outside his courthouse office last month was remembered Saturday for his zealousness in pursuing tough cases, his love of flying and his ability to tell stories.Hundreds turned out in a school auditorium to celebrate the life of Kaufman County Assistant District Attorney Mark Hasse during a 90-minute memorial service that included stories about the veteran prosecutor's tough and softer sides as well as vows to catch his killer.Hasse, 57, was shot multiple times the morning of Jan. 31 while walking from his car in a parking lot about a block from the courthouse. The brazen crime has sparked an investigation that includes both local and federal authorities, many of whom attended the ceremony Saturday.District Attorney Mike McLelland described how Hasse, who wasn't married and had no children, never backed away from anything while often telling stories that brought laughter heard throughout the courthouse.McLelland then turned to the effort to find Hasse's killer."He knows and I know there will be a reckoning," the DA said. "Too many people are focusing on that. That's not going to be a problem."The slain prosecutor's brother, Paul Hasse, also mentioned the search for the gunman."You honor him by the massive effort you are making to find out who did this," he said.Several speakers traced Hasse's career from his time as an assistant district attorney in Dallas in the 1980s to his decision three years ago to join the DA's office in Kaufman, 33 miles southeast of Dallas.Dallas attorney Marcus Busch, who worked with Hasse in the Dallas DA's office, called Hasse "the consummate prosecutor," describing how he rose from handling cases in misdemeanor courts to being the chief of the unit charged with prosecuting organized crime. In one well-known instance, Hasse's "wicked and clever intellect" led him to take on a case of murder by arson that had previously been rejected, and he gained a conviction, Busch said.Busch also spoke of Hasse's love of flying and how he recovered from severe head injuries after the vintage World War II aircraft he was flying crashed in Virginia. Busch said he began taking flying lessons himself because of Hasse's passion for it.Hasse left private practice to work as a prosecutor in Kaufman because "that's what his passion was," Busch said."I'd rather be in court trying a case with Mark than being in this room today," he said, stopping to gain his composure.Cooke County DA Janice Warder, another former colleague from Hasse's Dallas days, recalled working with him before computers put information at their fingertips. When questions would emerge from complicated autopsy reports or engineering documents, Hasse would have the answers, she said."Before there was Google, there was 'Ask Mark,'" Warder said.Above all else, Hasse was "ruthless when it came to fighting evil," she said.Justin Lewis, an officer with the Kaufman County Sheriff's Department who was an investigator in the county DA's office, also spoke of how Hasse "enjoyed putting criminals in jail." Lewis ended his remarks by saying the killer will be caught."Answers will eventually come," he said. "We must remain vigilant."