As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT 12000 FT NORTH OF MRB, CREW RECEIVED FORWARD CARGO DOOR WARNING MESSAGE. CREW RAN CHECK LIST AND RETURNED TO IAD. DECLARED AN EMERGENCY AND A/C LANDED WITHOUT FURTHER INCIDENT. MX INSPECTED THE A/C AND FOUND DOOR LATCH WAS NOT SECURED PROPERLY. PERFORMED OPS CHECK OF DOOR AND HANDLE, OPS CHECKED GOOD.