Speaking at an academic seminar at Chulalongkorn University medical school, Dr Ratplee PakAt of the Department of Surgery said he had studied pictures of the victims treated at hospitals around Bangkok.
He found that most suffered wounds to their legs and destroyed ankle tendons.
"I do not think that this was caused by tear gas canisters because we found severe wounds and black particles on destroyed tissue on their bodies. We are not sure that this is carbon or not," he said. Studying xray film of victims' feet, Ratplee said he found broken sole and toe bones.
These injuries could have been caused by direct attack such as hitting with a stick with powerful force. Some victims had shallow wounds and bruises on their faces. The severe wounds on their backs however had been caused by chemical burns. "Not an ordinary wound, but caused by heat," he added.
Dr Piyanun Mathuramon of Ramathibodi Hospital said he examined the dead body of Angkana " Bo" Radabpanyawoot who was killed while walking to the Royal Plaza with her mother and younger sister. He found a chemical compound like carbon on her body but no fragments of metal or plastic on her body.
"The severe wounds on Angkana's body were not found to contain any metal fragment from an explosive. We found only some amount of chemical compound which look like black carbon. We have sent this suspicious compound for study at the Thai Royal Office, " he said.