You could be:
aiding a felon
accessory before the fact
accessory after the fact
It's called a 'thief'
They are called a thief.
The Tasmanian devil is not called a thief.
a petty thief
Thief in Telugu is called దోకావు (Dokaavu).
Hades's symbol of power, a crown, is called the Helm Of Darkness in the Lightning Thief.
a beef thief is also called a beef bandit,beefate,beef crime syndicate
rustler
electron
A person who steals agricultural produce is typically called a "crop thief" or a "produce thief."
The fourth book in The Lighting Thief series is The Battle of the Labyrinth.
Don't know about "thief," but the Greek root "klepto-" means "steal." This may help.