After a user notifies the bank that he or she noticed a suspicious card transaction, the bank starts a CC fraud investigation.
The victim has to notify the bank regarding the fraudulent transaction immediately and no later than 60 days after the event. He or she must provide information about the exact amount of money lost, the date, and a description of why the transaction appears to be fraudulent. Then, the bank starts an investigation that has to be resolved in no more than 45 days. If after 10 days the bank finds out that fraud did indeed occur, the bank must reimburse the victim for the amount of money that was stolen.
The bank must notify the cardholder of the results of the credit card fraud crime investigation in writing. The cardholder has the right to ask for copies of any documents that the bank created or collected during the investigation process in the event that these documents influenced the banks decision. Hopefully, this answers the question of who investigates credit card fraud.