I am not an expert at Illinois crminal law, but I could see how the acts complained of could rise to the level of criminal conduct -- although it is highly doubtful most prosecutors would want to bring charges. The acts might be prosecuted as a criminal trespass (entry into a space she was not permitted to enter) or perhaps, depending on the circumstances, even burgulary; they may violate the state's theft of trade secret or confidential information laws. They may, again depending on all the facts, also be conspiracy, or conceiveably embezzlement
In any event your friend's actions are reprehensible and as they say in Holywood, "She'll never work in this town again".