More "what ICE actually does." HSI is a division of ICE. It investigates human trafficking, MS-13, etc. They're trying to shut down those investigating their crimes.
HSI has broad legal authority to enforce a diverse array of federal statutes. It uses this authority to investigate all types of cross-border criminal activity, including:
Financial crimes, money laundering and bulk cash smuggling;
Commercial fraud and intellectual property theft;
Cybercrimes;
Human rights violations;
Human smuggling and trafficking;
Immigration, document and benefit fraud;
Narcotics and weapons smuggling/trafficking;
Transnational gang activity;
Export enforcement; and,
International art and antiquity theft.
https://www.ice.gov/hsi