Another death and mass protests. What is ICE for Trump's presidency?

It is Agents of the Immigration and Enforcement Office (ICE) that implement the policy of mass deportations - 1 of Donald Trump's main electoral promises, and since inauguration 1 of the key actions of his administration. After the death of another individual shot by the officers of this service, she became possibly the most publically criticized formation in the United States. What is ICE and how has it changed under the current president?