This is an often-asked question, and I think the answer is that overall the island is quite safe.
However, with nearly 5,000 residents and at any one time several thousand visitors, you are always going to have a certain amount of crime, mostly petty thefts and break-ins but occasionally something much more serious. San Pedro will always be a magnet for a few bad apples who see "rich" tourists (and quite a few rich island residents as well) as easy pickings.
In tourist areas, it is always in the interests of the hotel and other tourism operators to downplay crime, but if you read the San Pedro Sun or just ask around you will hear a lot of stories about crime, a few involving tourists -- the occasional stabbing, mugging, rape or attempted rape and of course thefts and break-ins at hotel rooms.
If memory serves there have been three murders on or near the island this year, but two were in an execution-style murder on a boat from Corozal.
The worst crime on the island in my memory was the murder of a noted gardening writer, an American expat resident on the island, and her British friend, a few years ago -- they were horribly beaten and thrown into the sea late at night just south of town on their way back from a club. The murderer, from PG, was caught and convicted and sentenced to hang though as I recall he is still in prison.
Crime-free paradise? No. But in general the island is as safe as you could reasonably expect a resort island to be. Just use the usual precautions.
Crime happens everywhere. Just last week I was out of town and when I returned I found my office in a small town in North Carolina had been broken into, the second time in two years. This time the security system stopped the guy, and the cops almost caught him.
The only thing he got away with was a straw Guatemala hat I bought in Belize about 10 or 12 years ago. Fortunately, a police dog
found the hat and only chewed it up a little.
--Lan Sluder www.belizefirst.com