Hinnefeld began his career as a high school physics and math teacher before earning his Ph.D. in Nuclear Physics at the University of Notre Dame. He is an experimental nuclear physicist with a focus on reactions with astrophysical implications. He is involved in research at the Nuclear Structure Laboratory at the University of Notre Dame, the Joint Institute for Nuclear Astrophysics (JINA), and the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State. Hinnefeld has received several National Sciences Foundations grants and the IU South Bend Distinguished Research Award. One successful grant led to the building of an observatory on top of Northside Hall. Hinnefeld has mentored many students in research, leading to student publications as joint authors or separately from him. He has also been named to Indiana University's Faculty Colloquium on Excellence in Teaching, a selective honor. Beyond the classroom and his research he is very involved in faculty governance and has served as president of the Academic Senate at IU South Bend. He received his bachelor's degree in Physics from Hanover College in Indiana.