Most organ transplant patients are eternally grateful to the doctors and surgeons who extended their lives, but that's not the case with 41-year-old Nelson Flecha.

According to reports, the Orlando, FL, man tracked down his lead surgeon, Dr. Dmitriy Nikitin, and shot him dead in a parking garage at Florida Hospital.

After killing the surgeon, Flecha shot himself. Neighbors and friends say that he was a "bitter and angry man" who appeared disgruntled after his liver and kidney transplant.

Police are still unsure why Flecha targeted his surgeon, though they believe it's because he believed his operation was a failure.