"You can't be fearful. You just have to be prayerful," Wiley, a Kaufman County Republican court-at-law judge, said Wednesday after she was appointed. "You have to know that we've got good people that are going to protect us until justice is done.
"I think I can do this and not be scared," she said.
Wiley's appointment must be confirmed by the state Senate, The Dallas Morning News reported.
First Assistant District Attorney Brandi Fernandez has been interim district attorney since McLelland's death March 30, when he and his wife, Cynthia, were shot and killed in their home.
Kaufman County assistant prosecutor Mark Hasse was shot and killed Jan. 31 while walking to the courthouse.
No arrests have been made and the cases haven't been officially linked to the same suspect or suspects.
Bruce Bryant, an investigator with the Kaufman County district attorney's office, said the atmosphere in the office was tense.
"I don't think things will settle down until an arrest is made," Bryant told the News. "It's an open wound. It never heals."
Wiley said that the best way to move forward was to keep working, the News said.
"I'm really appreciative of the governor for appointing me, for thinking that I could step into this chaos that's been going on in our county," Wiley said.