As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APROX 3 MINUTES AFTER TAKEOFF, DURING CRUISE FLIGHT AT APROX 120 KNTS AT 1500 MSL, 1000 FT AGL, THE CO PILOT DOOR SLIDING WINDOW DEPARTED THE ACFT DURING FLIGHT AND MADE CONTACT WITH THE REAR SLIDING DOOR AND THE FUSELAGE. NO CHANGE IN ACFT CONTROL WAS DETECTED AND THE ACFT RETURNED TO BASE.