Aid and abet
Definition 1 of 1
Pro Tip 1/3Legality Aspect
Emphasizes involvement in illegal or wrongful activities, not just general assistance. 
The accountant was fired for aiding and abetting the embezzlement.
Pro Tip 2/3Active Participation
Indicates active help or encouragement, more than just being present or aware. 
He didn't just watch the robbery; he aided and abetted by acting as a lookout.
Pro Tip 3/3Serious Consequences
Use highlights potential serious legal consequences for the helper. 
She risks being charged for aiding and abetting if she hides her brother, the fugitive.