Pol Lt-Col Viradol Tubtimdee of Thong Lor police station said Mr Vorayuth's blood sample contained 63 milligrammes of alcohol per 100 millilitres of blood, or a reading of 0.063%. The legal blood-alcohol limit in Thailand is 0.05%.
"Mr Vorayuth will face an additional charge of drunk driving," Pol Lt-Col Viradol said.
He already faces charges of failing to stop after an accident and reckless driving causing death.
Metropolitan Police Bureau chief Kamronwit Thoopkrachang said on Thursday he had ordered the dimissal from the force of Pol Lt-Col Pannapon Nammuang, an inspector at Thong Lor police station.
He said Pol Lt-Col Pannapon first arrested a scapegoat, Suwes Hom-ubon, in an attempt to protect Mr Vorayuth. Mr Suwes is Mr Vorayuth's aide and chauffeur.
"Pol Lt-Col Pannapon has 30 days to appeal," Pol Lt-Gen Kamronwit said.
Pol Lt-Col Akharawin Sukhonthawit, deputy chief of Thong Lor station, said a disciplinary committee had ruled that Pol Lt-Col Pannapon acted illegally in trying to place blame on an innocent person to protect an offender.
About 5.30am on Monday, on Sukhumvit road, a Ferrari driven Mr Vorayuth, 27-year-old grandson of Red Bull energy drink founder Chaleo Yoovidhya, slammed into the rear of the motorcycle ridden by Pol Snr Sgt Maj Wichian Klanprasert, killing him instantly.
Mr Vorayuth fled to his home in soi 53 after the crash, which happened near the mouth of soi 47.
Metropolitan Police Bureau deputy commissioner Jarumporn Suramanee said on Wednesday that a forensic investigation concluded that the Thong Lor police officer did not suddenly cut in front of Mr Vorayuth's Ferrari with his motorcycle, as claimed, but was hit straight on from the rear by the sports car, which was travelling at high speed.