4 that we know of!
True story: a few years back there was a big story in Canada about a Canadian Air Force Colonel who was suspected of murdering two women. He eventually confessed and pleaded guilty. After that happened police departments nationwide searched their cold case files to see if he might be involved in anything else. They did so because as an Air Force officer he had,over the years,been stationed at bases all over the country. IIRC they didn't find anything else to charge him with.