i mean, we really did love him. it was devastating when he was gone. reporter: monday morning, four days after the murder of mark cassie, fellow prosecutor shannon abare, returned to worker with a heavy heart. of course, it was a hard monday in our weekly meeting without mark. our whole office was devastated. i mean, his door was closed. reporter: security remained tight in and around the courthouse. the people inside took on a bunker mentality. folks were trying to deal with what happened. nobody has ever done this before. this is new territory for everyone. reporter: his colleagues were terrified. and many wanted to carry guns for protection. district attorney mike mcclelland made it easier for everyone to get concealed
any assistance that anybody can give us in finding the people who did this will be greatly appreciated. reporter: d.a. mcclelland had it tough, he an office to run while mourning a friend. how hard was it for him to come back. it was very difficult. he talked a lot about the case. reporter: and the case was about to get bigger with another murder. only this one crossed another line. a very sacred line. reporter: coming up, another member of law enforcement gunned down. the colorado head of the department of corrections was shot here in his front door. had mark cassie s killer struck again? when dateline continues. ntinu. and grab every moment. made with superior softness, for your comfort.
goldilocks and listened to a radio on the manhunt for him. when police would get close, he would vanish into the woods. that wasn t until, of course, they got him. right now, new developments this the search for suspects in the murders of three people, including two prosecutors. texas police have arrested robert miller who accused of threatening a district attorney in the same county where two other people were killed. d.a. mike mcclelland pictured here and his wife sin hi a, both found shot at their home a week ago, and their killings came two months after assistant d.a. mark cassie was gunned down near the kaufman county courthouse. dominic live from our los angeles bureau with more on this. don? harris, that man the authorities have arrested is robert miller from texas, and is now charged with making a terrorist threat. he s being held on a $1 million bond for allegedly posting that threat against assistant kaufman, county district attorney for an unnamed district