A Criminal Court inquest recently found that taxi driver Phan Kamkong was killed by guns used by military personnel during the crackdown.
Chavanond alleged that the inquest was a one-sided trial in which the accused could not defend themselves and that no one was pinpointed as the shooter.
He insisted the security body set up to contain the protests issued no order to use force against or kill civilians, only to keep order in dealing with "black shirts," armed men who served as guards for the demonstrators.
"To use the court's inquest to conclude that the two men had the intention of murder was groundless and against the law," Chavanond said.
He said both Abhisit and Suthep "are ready to prove their innocence," and that "those who brought up false charges will have to take responsibility."
DSI chief Tharit said factors leading to the planned charges include the continuing use of force over time and the killing of civilians without resorting to other methods of controlling protesters.