I think I've got a mental block with this one.
I'm visible on a small tile with 1x enemy who is also on the same tile as me. I kill him with a silenced weapon. No other enemies adjacent, am I now stealthy ? Or do I have to move to another small tile or 2AP medium tile to become stealthy?
In every instance where you are visible, the only way to become stealthy is to move (Unless you have a uniform, or some other ability that turns your stealthy)