The body of the 31-year-old Bubic will be taken to a local hospital for an autopsy to establish the exact cause of his death.
The murder of the 45-year-old police officer, Ranko Grkovic, occurred in Split last night, when three police officers, including Grkovic, approached a car driven by a 32-year-old man, with Bubic in the passenger seat.
When they asked Bubic to produce his ID, he reached for a gun and fired several times at Grkovic, after which he left the car and escaped.
Shocked by Bubic's reaction, the driver remained sitting in the car and was arrested. He is not suspected of active involvement in the murder for the time being.
Bubic, a former convict, was known to the police for a number of criminal acts, including two attempted murders, a robbery, several cases of grand larceny and drug abuse.