Dr Dmitriy Nikitin was shot and killed by his former patient Nelson Flecha: Police

Police in Orlando, Florida, say an organ recipient shot and killed the doctor who saved his life.

Authorities are still trying to figure out what caused 53-year-old Nelson Flecha to kill Dr. Dmitriy A. Nikitin in the parking garage of Florida Hospital main campus last Thursday evening.

Reports say Flecha had been patiently waiting for the 41-year-old doctor in the garage.  It is believed patient and doctor spoke for a brief moment before the shooting.  Authorities say after Flecha shot the doctor, he walked to a different level of the garage and shot himself to death.

Hospital officials say Dr. Nikitin performed a liver and kidney transplant on Flecha about a year ago.

Dr. Nikitin, who is originally from Russia, leaves behind a wife and four children.

Neighbors say Flecha never seemed happy, even though he had been given a new lease on life with the double transplant.

It is unclear whether he had suffered complications from the surgeries.