MANISA — Turkey's prosecutors appointed to investigate the Soma mine accident have begun to collect testimonies from witnesses and victims, according to the prosecutor's office.The views of an occupational safety expert committee, composed of electrical engineers and experts in mining, will also be included in the investigation.Prosecutors on duty in Soma are taking necessary measures to identify evidence at the scene of the accident, the prosecutor's office announced.The Soma mine accident is the deadliest in Turkey's history, surpassing an explosion of firedamp - a flammable gas found in coalmines - that killed 263 miners in Zonguldak in 1992.What caused the blast inside the mine is yet to be determined, but suspicions are centered on an explosion and fire, which resulted from an electrical fault.Turkey's Energy Minister Taner Yildiz said any negligence on the part of officials or the company managing the mine will be punished. In a press conference on Friday, Soma mine managers denied claims of negligence and said they took all necessary measures to prevent such an incident.They said in a written statement earlier that the disaster was "inexplicable" from a technical standpoint and unprecedented for the industry with respect to its causes.