inside job

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A crime perpetrated by, or with the help of, a person working for or trusted by the victim.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic A crime or other illicit action committed by or with the help of someone either employed by the victim or entrusted with access to the victim's affairs and premises.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun some transgression committed with the assistance of someone trusted by the victim