Have you looked in John Brunner's excellent book, The Colt Pocket Hammerless Automatic Pistols? I have the first addition, but would need the serial # if you want help. (see pgs 100-115) Most aren't listed by individual numbers, except for general officers, but that's where I would start. If Colt shipped it overseas or to a purchasing agent, a letter would be helpful; but they are pricey and take months to receive. If it somehow got the markings after going through a few hands a letter probably won't help.
Doesn't appear to be Shanghai Municipal Police.
Possible other foreign shipments listed in Brunner's book include:
Tientsien British maritime customs police, Portuguese Macao colts, Malay Straits settlements police , Japanese, Southern Rhodesia, Western Australia police, Java, Dutch.... I
Interestingly Japanese Prime minister Hideki Tojo shot himself with a Colt 1903 32 on 9/11/45. There were 20,000 shipped to various dealers in Japan, including 140 to occupied Manchuria and 50 to occupied Korea.
Also over 10,000 went to Phillippines, 10,000 to Thailand and 8,000 to Java.
Ted