>> it's mark hasse. oh, my god, it's mark hasse. he's an assistant district attorney. >> reporter: mark hasse, dedicated prosecutor, dearly-loved by his colleagues, shot right outside the courthouse. stunning onlookers and police. >> it's nothing you could prepare for. >> reporter: who would even attempt such a brazen attack? >> did that tell you these two knew each other? >> that seemed very personal to me. knew each other? >> that seemed very personal to me. . .tpb1ñ . . . >>> a beloved prosecutor had just been shot outside the courthouse in kaufman, texas, during the morning rush. officer++ he was laying on the street. >>> you're seeing the dramatic images from the officer's onboard camera. >> it was a woman and it looked like she was doing cpr. >>> that woman had witnessed the shooting from her car. saw the shooter flee and then tried to help mark. now he was taking over and going on instinct and adrenaline. >> when you pull up, it is nothing you can prepare for. >> he knew right away it was bad. >> he looked at me and then he s

but then the texas task force found out ebel's gun was not the weapon that killed mark hasse. ase was going nowhere. >> fewer and fewer lead were coming in to the investigation. >> the command post of shut down, leaving just a small group to work full time on the case. >> slowly we kind of trickled back to our daily duties. >> the passage of time was allowing shannon ebert to finally get her equilibrium back. >> i just wasn't checking out my window as constantly or worried about when i pull out of my garage if someone would be waiting there. i think you start letting your guard down again, and life kind of took over. >> same thing for hard-nosed d.a. mike mcclelland. according to his stepdaughter, christina -- did things naturally start getting back to normal? >> yeah. i think more a sense of normal. it was still kind of at the forefront of we haven't found anything yet, we haven't solved this yet. but life moves on. >> for the mcclellands, moving on men spending-- meant time spending time with family, something mike enjoyed since marrying cynthia when christina was just 10 yea