answer:“Person of interest” is a British police term that’s been adapted in some parts of the US. “Suspect” has such a presumption of guilt that it’s no longer useful. After all, just because a person is a suspect doesn’t mean that they did it! Eventually, though, the same thing will happen to “person of interest”, too, as it gets tied to meaning “that’s the ruddy bastard we think wot did it!”, so not to worry. Orwell never reckoned on the euphemism treadmill, did he?