ST. LOUIS, Mo. (KSDK) - SSM Cardinal Glennon Children's Medical Center is mourning the loss of a veteran physician.

Dr. Casimir "Casey" Firlit passed away on Tuesday, December 18 at 73-years-old.

According to Cardinal Glennon Spokesperson Ashley Wiehle, Dr. Firlit was Director of Reconstructive Urology, Neuro-Urology and Fetal Urology at SSM Cardinal Glennon since 2003. He also worked at St. Louis University School of Medicine.

Dr. Casimir Firlit received his Ph.D. in Pharmacology from Loyola University in Chicago, and was featured as one of the Best Doctors in St. Louis from 2005 through 2012.

Firlit previously served as Chief of Pediatric Urology at Children's Memorial Hospital in Chicago and taught at Northwestern University.