SP Mahantesh, whose condition turned critical yesterday, died following a cardiac arrest, hospital sources said.
"Mahantesh heart stopped at 5.30 am. We tried our best to revive him, but failed", a doctor, who refused to be named, said.
48-year-old Mahantesh, who suffered head injuries in the alleged attack by unidentified persons on May 15, had been on life support system since the last two days.
He was found unconscious near a hotel here while returning home in his car and shifted to the hospital after passerby noticed him and informed his family.
The KAS officer, known for his integrity, was working as deputy director of the audit wing in the state's cooperative department and had reported irregularities in different societies involving some officials and political figures.
Police have formed a special team to track down the culprits, but are so far clueless.
This is the second death of an official of the state government after an Assistant Conservator of Forest, Madan Naik, who was assaulted by a group of tourists at Dandeli in Uttara Kannada district on May 6.
Naik was attacked when he objected to the tourists feeding crocodiles at a private resort.
The government has ordered CID probe into Naik's death and the police have arrested six persons in this connection.