The court also upheld the life sentence on two other accomplices - Winyu Rattanawannee and Anont Pantharat.
According to the lawsuit, on May 27, 2006 the three opened fire at a vehicle in which Mrs Kobkul was travelling, killing her instantly, at Khao Ngu intersection in Muang district of Ratchaburi province.
The court of first instance initially sentenced all three of them to death. Since Winyu and Anont confessed during the investigation, the death sentence was reduced to life.
The three appealed. The Appeals Court upheld the lower court's verdict.