A computing network system including a historical authorization database, a lost and stolen card (LSC) database, an account data breach (ADB) database, and a compromised identification (CI) computing device is provided. The CI computing device retrieves a set of historical account identifiers associated with historical transactions of a candidate merchant from the historical authorization database. The CI computing device compares the historical account identifier to lost and/or stolen (LS) account data stored by the LSC database and breach data stored by the ADB database. The CI computing device generates a compromised account message when a historical account identifier has a matching account identifier within the LS account data and/or the breach data. The compromised account message includes the matching account identifier and an associated reason code indicating a cause of compromise. The CI computing device transmits the compromised account message to the candidate merchant for review and analysis.