The overly-simplified answer is "Yes". Drew's Regiment, the 1st Cherokee Mtd Rifles (CSA), was already hostile to the Confederates before Pea Ridge. Drew's Regiment was hostile to the Watie-led faction of the tribe since before the forced removals in 1838-39. They refused to fight against Opothleyahola's "Loyal Creeks" at Chusto Talasah (Dec 1861) and they were only enticed to go to Pea Ridge with the strong urgings of Chief John Ross and the promise they would be paid in Arkansas. All but about 75 of the regiment defected during the 1st Indian Expedition, July 1862.
There is no proof to their claim that they killed Confederate wounded at Pea Ridge -- some argue they made up the story to convince the US military they had really been "loyal" all along (which is somewhat true).