ABETTOR

• Criminal crony

• Friend in crime

• Getaway car driver, for example

• Getaway driver, e.g.

• Helpful sort

• Joint caser, e.g.

• Lockout for a holdup man

• Lookout man, for example

• Lookout, maybe

• One aiding in wrongdoing

• Partner in crime

• Perpetrator's pal

• Thief's aide

• Wheelman, for example

• Wingman, maybe

• One who helps or encourages or incites another