After practicing briefly in Dallas, Murr returned to Junction to establish his own law office. He moved rapidly in local political circles, having been elected county attorney and then county judge of Kimble County, a position which he filled for five years until September 30, 2013, when he resigned to run for the Texas House. Murr's grandfather had also held the same positions of county attorney, county judge, and state representative, with a stint as well as House Speaker. In 2011, then Governor Rick Perry named Murr to the Concho Valley Regional Review Board. As county judge, he was chairman of the regional Juvenile Board, which supervises probation in several counties. In the Republican primary election for state representative held on March 4, 2014, Murr handily led a five-candidate field with 10,089 votes and was placed into a runoff election on May 27 with the runner-up, Robert Earl "Rob" Henneke and a lawyer in Kerrville, who received 7,051 votes. Murr then defeated Henneke, 9,387 to 6,100. In the November 4 general election, Murr had no Democratic opposition and defeated the Libertariannominee, Maximiliam Martin, 36,878 votes to 4,139. The District 53 House seat was vacated after twenty-six years by Harvey Hilderbran of Kerrville, who ran unsuccessfully against Glenn Hegar for Texas Comptroller of Public Accounts in the March 4 primary. Murr won his second term in the House in the November 8, 2016 general election. With 54,741 votes, he defeated Democrat Stephanie Lochte Ertel of Kerrville, who polled 14,256 votes, and the Libertarian Brian Holk, who trailed with 2,170 ballots. Murr secured a third term in the state House in the general election held on November 6, 2018. With 52,813 votes, he again defeated Democrat Stephanie Lochte Ertel, who polled 14,407 votes. Ertel finished with 151 more votes in 2018 than she drew in 2016.
Personal life
Murr lives on the family ranch in Kimble County with his wife, Amanda, and his son, Coke. Murr raises cattle and operates the Telegraph Title Company in Junction. Murr sits on the board of Junction National Bank. He is a past president of the Farm Bureau of Kimble and Edwards counties and his local Rotary International. He is a past chairman of the executive committee of the Concho Valley Council of Governments. He has also served on the Concho Valley Transit District, the Kimble County Historical Commission, the Kimble County Youth Show, and the Hill Country Fair Association.