there were no shell casings? >> yes, it told us that it was a resolver. >> reporter: that's because resolvers keep the bullet casings inside the begun after firing. i can only imagine how ti-- how terrified he was in the final moments. >> he was doing what he did every day. he was going to work. >> reporter: now they feared he died for the work, and they could be next. no one felt safe. >> we didn't know if there were people waiting to shoot us. >> reporter: the courthouse was locked down in the morning and closed for the day. they were given extra security. >> they were walking us to our cars carrying huge rifles and guns. >> reporter: when did it sink in to you that it could have been me. you walk in to work with mark. your office is there. >> that was the immediate fear. it could have been any of us. >> we lost a really, really good