In Skyrim, I only pickpocket bandits (basically to raise my skill level with no chance of detrimental effects), and only right before I kill them. However, when I left a bandits' hideout recently, there were thugs waiting outside with a contract signed by a bandit. Is the lag between pickpocketing and killing enough that the bandit could have hired a thug?
Yes, dead targets can send thugs after you. If I remember from looking at the script itself, it triggers right as you steal something and will spawn thugs as one of your next few encounters.
If the target is dead, it's incidental as far as the bandits are concerned.