You can use suspiciously when you are describing something that you think is slightly strange or not as it should be. He lives alone in a suspiciously tidy flat in Notting Hill Gate see also suspicious
If you say that one thing looks or sounds suspiciously like another thing, you mean that it probably is that thing, or something very similar to it, although it may be intended to seem different. The tan-coloured dog looks suspiciously like an American pit bull terrier