Harris County prosecutor Kelly Siegler, known for effective theatrical tactics in the courtroom, is set to run for district attorney as a Republican after the withdrawal of her boss, District Attorney Chuck Rosenthal.
Siegler said she plans to file paperwork today for a place on the party's March 4 primary ballot.
She has been an assistant district attorney for 21 years.
Siegler said she is running because the district attorney's office has a sterling reputation "and those of us who have made it our career want to make sure it retains that reputation."
The agency is known nationwide as the pace-setter for seeking the death penalty and has been rocked by evidence errors made by the Houston police crime lab.
Siegler, who was not among the assistant district attorneys whom party leaders had interviewed as possible candidates in recent days, said she was unsure whether some of her colleagues will run now that she is a contender.
Prosecutors Denise Bradley, Steven St. Martin and Marc Brown expressed interest Wednesday.
Defense lawyer and former prosecutor Jim Leitner already is on the ballot, and the Republican winner will face Democrat C.O. Bradford, the former Houston police chief, in the November general election. Leitner, however, indicated he might withdraw if another Republican candidate looked to him like a top-notch prospect.