Slagel, elected to the city council in 1987, served as mayor from 1991 to 2007, then again from 2009 to 2011. He is currently the president and CEO of CapitalSoft, a company that develops and implements program management software for the public and private sector construction markets.

A member of the Texas Transportation Institutes Advisory Council, Slagel graduated from Illinois State University with a bachelor's degree in industrial technology and received a master's degree in business administration from Amberton University in Dallas.