BANGKOK -- Thai police said Thursday they would add drunken driving to the charges against a Red Bull energy drink heir accused of killing a police officer while speeding in his Ferrari and fleeing the scene.

Tests taken in the hours after Monday's crash showed 27-year-old Vorayuth Yoovidhya's blood-alcohol content was 0.063 percent, exceeding the legal limit of 0.05, said Police Lt. Col. Wiradon Tubtimdee.

Vorayuth was summoned to hear the new charge of drunken driving, which could result in a stiffer penalty if he is convicted. Police charged him already with causing death by reckless driving and escaping an arrest. He has not yet reported to police to hear the new charge, according to Wiradon.

Vorayuth's lawyer has said his client was not drinking before the accident.

"I understand that after the crash and his surrender, Boss drank that night to relieve his tenseness ... but he did not drink before the incident happened," family lawyer Samak Chaowapanant told the Bangkok Post, referring to Vorayuth by a nickname.

Police said Vorayuth admitted he was driving the Ferrari that struck the officer's motorcycle but said the officer swerved in front of his vehicle.

Witnesses said the Ferrari dragged the officer's body down the road before speeding away, but police followed oil streaks at the crash site into the gated estate of late Red Bull founder Chaleo Yoovidhya, one of Thailand's wealthiest men before he died this year. The sports car had a badly dented bumper, scuffed hood and cracked windshield.

Forensic scientists attempted to calculate the speed of the Ferrari using footage obtained from nearby closed-circuit cameras that showed the vehicle coming on Bangkok's Sukhumvit Road before it crashed with the motorcycle.

"We will need more footage at different spots to be more precise, but right now it's certain that the car was coming at more than 100 kilometers (62 miles) per hour," said Sathon Vijarnwannaluk, a forensic expert on the investigation team.

Police have said they will conclude their investigation by the end of the month and forward it to prosecutors for court proceedings.

Bangkok police commissioner Comronwit Toopgrajank on Thursday expelled a local police superintendent who attempted to cover up the crime by turning in the family's driver, instead of Vorayuth.

The Yoovidhya family was ranked the fourth richest in Thailand this year by Forbes magazine with a net worth of $5.4 billion. They own a wide range of businesses, including shares in the energy drink brand, hospitals, real estate and a sole authorized importer of Ferrari cars in Thailand.

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  • Deputy Metropolitan Police Commissioner Anuchai Lekbamroong answers questions from reporters regarding the arrest of Vorayuth Yoovidhya, a grandson of the creator of the Red Bull energy drink, at the headquarters of the Metropolitan Police Bureau in Bangkok, Thailand on Tuesday, Sept. 4, 2012. (AP Photo/Sakchai Lalit)

  • In this photo taken on Sept. 3, 2012, Thai police officers look at a motorcycle and a Ferrari car that involved in a hit-and-run accident during the investigation at Thong Lor police station in Bangkok, Thailand. (AP Photo)

  • A Thai police officer examines a damaged Ferrari in the garage of a home of Chaleo Yoovidhaya, the creator of the Red Bull energy drink on Monday, Sept. 3, 2012 in Bangkok, Thailand. (AP Photo)

  • Vorayuth Yoovidhya

    Vorayuth Yoovidhya, a grandson of late Red Bull founder Chaleo Yoovidhaya, is taken by a plain-clothes police officer for investigation on Monday, Sept. 3, 2012, in Bangkok, Thailand. (AP Photo)