Brian E. Nelson

Responsible for operational leadership of the Treasury's financial intelligence and sanctions apparatus at a time when Tornado Cash was designated by OFAC. Supervised the coordination between Treasury policy teams, law enforcement partners and sanctions implementation, which produced targeted listings of protocol addresses and guidance that elevated compliance requirements across custodial and non‑custodial service providers. The operational decisions made under this portfolio affected how quickly and how broadly exchanges, custodial platforms and other intermediaries implemented monitoring and blocking of Tornado Cash‑linked flows. Those coordination choices also informed evidence packages and public advisories used by prosecutors and international partners pursuing arrests and asset freezes tied to mixer activity. By directing the interface between policy articulation and enforcement mechanisms, the office reshaped immediate market access for users interacting with Tornado Cash and set enforcement playbooks for future actions against protocol infrastructure. The practical result was a sustained change in how on‑chain mixers were treated by compliance teams and a tightening of relationships between analytics firms and regulators.