The teenager was killed in a car accident on the A2 motorway near Velden on Wednesday morning.
When police went to notify the young man's parents they found the couple dead in their ground floor apartment - they had been stabbed in the night.
Police are now searching for clues as to whether the 19-year-old murdered his parents and whether the car accident was in fact a suicide.
A neighbour of the dead spouses reported hearing a loud argument at 3 or 4 in the morning.
A highway patrol was called to the scene of an accident on the A2 at 6:23am after a BMW 320 crashed at extreme speed into a truck, in rainy conditions.
The sports car was totally destroyed and the 19-year-old mechanic was already dead by the time a first aid team arrived. Police have said there were no witnesses to the crash and it is difficult to say whether it was an accident or not.
When police arrived at his parent's address they found a 40-year-old woman and her 50-year-old husband lying on the living room floor. They had been stabbed to death with a kitchen knife.
"There were traces of blood all over the apartment," police spokesman Rainer Dionisio said.
The suspected murder weapon was found in the living room. Police think that the son lived at home with his parents.
An older son, 21, lives at another address in Carinthia. Police hope to question him on Thursday and he is receiving trauma counselling.
An autopsy of the three bodies will take place on Thursday afternoon.
The dead woman worked as a nurse and her husband was a retired truck driver.