MD-11 First Officer reported receiving messages indicating possible fire in cargo hold during cruise. Flight crew diverted and performed a normal landing. Postflight temperature readings done by airport responders were normal.

Narrative

Operating from ZZZ1-ZZZ; past our ETP. We received a CARGO FLO FORWARD DISAG LEVEL 1; the Captain and I reviewed that alert by referencing the QRH and noted no action was required. Just a few minutes after that indication we received a LEVEL 3 CRG FIRE LWR; at this time the Captain took the controls and I read this QRH for both of us to hear and confirm the actions required. Once the checklist was completed and not knowing the severity of the fire we [requested priority handling] with ATC via CPDLC; changed destination; to the closest airport to our present position ZZZ confirming it had suitable weather; then contacted company via SatCom to inform them of the situation and to get information of cargo being hauled. Once all checklist and notifications were made I got up to get the jump seater from the bunk to come upfront to provide another pilots prospective. At this point we still had about 90 mins remaining in flight; the Captain lead discussions about ditching; evacuating; system review of cargo fire indications; location of emergency equipment. We continued to monitor the time of fire bottle activation and knew the second bottle would need to be activated while on approach. We loaded an ILS CATIII for our approach into ZZZ. Once on VHF frequency we talked to ATC about our situation and our plans of stopping to have AARF (Airport Rescue and Firefighting) evaluate the aircraft prior to taxing into the ramp. We were receiving vectors for the approach the DISCH CARGO AGENT displayed on the EAD (Engine and Alert Display); as briefed I activated the second bottle. We auto landed the aircraft and felt it safe to clear the runway before getting AARF to get a temperature reading. Once we get clearance that the temp was in dating normal and all personnel were clear we taxied to the ramp. Performed a normal shutdown and exited the aircraft via the stairs. Ending my report I would like to add that this abnormal situation went smoothly thanks to the Captain setting the tone" at the beginning of the trip and each flight; she made sure everyone knew to speak up including jumpseaters; made us part of the decision process; took input and explained her decision process. There were no questions on what the game plan was thanks to her leadership. Fire? Smoke? Faulty smoke/fire detection? Faulty MSC (Miscellaneous System Controller)? Not sure; we didn't get a detector fault so it leads me to believe that it was an actual smoke event. These type of events can't be prevented. Unless this was a maintenance issue by not cleaning sensors or monitoring faults in the system that don't show to the crew."