Prior to becoming an academic, Professor Gestring has worked as a Death Investigator, DNA Analyst, supervisor in a Crime Scene Reconstruction unit,  supervisor in the World Trade Center Identification Unit, and a television consultant for Law & Order and Cosby Mysteries as well as a Forensic Science Consultant on active casework. He is a fellow of the American Academy of Forensic Sciences (AAFS) and member of the International Association of Identification (IAI) national and New York chapters. He also currently holds a certification from the IAI as a Senior Crime Scene Analyst.

Professor Gestring has taught at three Forensic Science Programs in the North East.  At Pace University, he created and developed the Undergraduate and Graduate Forensic Science Programs which he directed for their first five years. He is currently the most senior site evaluator for the Forensic Science Education Program Accreditation Commission (FEPAC) and is the current President of the Council on Forensic Science Education (COFSE).  Professor Gestring has also served the American Board of Criminalistics (ABC) as a member of the Examination Committee for the Forensic Science Aptitude Test (FSAT).

His main passion is to increase the quality of forensic science from the inception of the investigation through the legal proceedings. In recognition of this goal, Professor Gestring was appointed by New York City Police Commissioner Raymond Kelly as the only external member of a commission responsible for the oversight of Forensic Science in New York City.

This overarching goal is also responsible for a broad research interest encompassing forensic science pedagogy through methods of increasing the quality of information obtained from crime scenes.  Professor Gestring has also been involved in several initiatives to use forensic applications to stimulate science education.