The province's Special Investigations Unit is probing the circumstances surrounding the death of a prisoner who was in OPP custody in Kenora. The 42 year old woman died in a weekend traffic accident on Highway 11-17. The SIU's Monica Hudon says they are looking for witnesses specifically the driver of a dark pick up truck who may have seen what happened. Hudon says there are three SIU investigators in Kenora looking into the tragedy.