Fraud:  Wrongful or criminal deception intended to result in financial or personal gain.

Oxford English Dictionary

Scam: A fraudulent scheme performed by a dishonest individual, group, or company in an attempt obtain money or something else of value. Scams traditionally resided in confidence tricks, where an individual would misrepresent themselves as someone with skill or authority, i.e. a doctor, lawyer, investor. After the internet became widely used, new forms of scams emerged such as lottery scams, scam baiting, email spoofing, phishing, or request for helps. These are considered to be email fraud

businessdictionary.com

Forensic Accounting: The definition of 'forensic' is 'relating to the courts', and forensic accounting covers all accounting analysis that is suitable for court. ... Investigative accounting is more often associated with the investigations of criminal or regulatory matters.

University of Melbourne, Faculty of Business and Economics