Field experts conducting a fourth excavation at Oaklawn Cemetery in Tulsa, looking for graves of possible 1921 Race Massacre victims, have located another three, possibly four, unmarked graves. State Archaeologist Dr. Kary Stackelbeck says teams will now try to determine whether the graves meet certain criteria for further excavation and exhumation. That criteria includes plain coffins that contain the remains of young black males showing possible signs of trauma.