Which are the primary sources of information for a sanctions investigation?

Sanctions investigations rely primarily on the factual evidence contained in transaction activity and on authoritative, government-issued sanctions lists. Transaction details provide information on counterparties, payment paths, goods, and purpose. Official blocked-person lists such as OFAC, EU, UN, and national export-control lists provide the authoritative basis for sanctions matching. News, social media, and internal correspondence may supplement context but are not primary sources.