HOUSTON, June 13, 2013 (GLOBE NEWSWIRE) -- Clarence P. Cazalot, Jr, chairman, president and CEO of Marathon Oil Corporation (NYSE: MRO) has elected to retire on Dec. 31, 2013, after almost 14 years leading Marathon Oil and 41 years in the oil and gas industry. Cazalot will continue as executive chairman through Dec. 31, 2013. The Marathon Oil board of directors has elected Lee M. Tillman to the board of directors and to succeed Cazalot as president and CEO effective Aug. 1, 2013. The board of directors intends to nominate Dennis H. Reilley, currently Marathon Oil lead director, as non-executive chairman upon Cazalot's retirement. Tillman, 51, most recently served as vice president of Engineering for ExxonMobil Development Company where he was responsible for all global engineering staff engaged in major project concept selection, front end design and engineering. He holds a Bachelor of Science degree in chemical engineering with honors from Texas A&M University and a Ph.D. in chemical engineering from Auburn University. Following his formal education, Tillman began his career in the oil and gas industry at Exxon in 1989 as a research engineer. He has extensive operations management and leadership experience that has included assignments in Jakarta, Indonesia; Aberdeen, Scotland; Stavanger, Norway; Malabo, Equatorial Guinea; Dallas and New Orleans. "Speaking for the entire Marathon Oil board of directors, we are very pleased to welcome Lee to the Company. His strong leadership skills and extensive experience in global operations, project execution and leading edge technology will be invaluable in confronting the challenges facing our Company and industry," said Cazalot. "I look forward to working with Lee, the rest of our executive leadership team, and all our dedicated employees over the next six months as we transition to his leadership and continue to execute on our well defined strategy."