The woman was beside a pickup truck in the 5200 block of Mosson Road, distraught over finding the remains of a man she knew in the vehicle's bed.
Marc Mitchell, the mechanic, saw the pickup parked in the grass upon arriving at work shortly before 6 a.m., but he thought nothing of it.
Mitchell said he was working on a truck between 8:30 and 9 a.m. when he heard screaming.
"With the motor running and everything I heard this blood-curdling scream," Mitchell said. "Something you hear ... like on horror movies."
Police are treating the case as a homicide.