As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO LAS DUE THE FLIGHT CREW REPORTING THAT WHILE IN FLIGHT OIL QUANTITY IN NUMBER 1 ENGINE FELL TO 0. PRESSURE STAYED. THE AIRCRAFT LANDED SAFELY AT LAS WITHOUT FURTHER INCIDENT. MAINTENANCE SECURED LINE ON LOW OIL PRESSURE SWITCH THAT HAD LOOSENED INFLIGHT AND ACCOMPLISHED A SATISFACTORY LEAK & OPS CHECKED WITH NO ISSUES NOTED.