Tim has lived in St. Charles County, Missouri, all his life. After leaving St. Charles West High School, he obtained his undergraduate and Juris Doctor degrees from the University of Missouri. After graduating from law school, he started a private practice in St. Charles and worked as an assistant prosecutor for the Missouri city of O'Fallon.
Later, Lohmar held the position of St. Charles County Municipal Court's first-ever municipal judge. Then, in 2010, he was chosen to work for the State of Missouri as an associate circuit judge. He was finally appointed to the position of St. Charles County Prosecuting Attorney in 2012 by the St. Charles County Executive, and he was re-elected to that position in 2014 and 2018. Currently, Lohmar is running unopposed for reelection to a third term.