A look at how immigration authorities make arrests

Astrid Galvan and Nomaan Merchant The Associated Press
A person is arrested during a Feb. 7, 2017, operation by U.S. Immigration and Customs Enforcement aimed at immigration fugitives, re-entrants and at-large criminal aliens in Los Angeles. [Charles Reed/U.S. Immigration and Customs Enforcement via AP]

Some questions and answers about how U.S. Immigration and Customs Enforcement operates:

What ICE can do

Immigration and Customs Enforcement is in charge of arresting and deporting immigrants who lack legal status.

One common method of finding and arresting people who are known to be in the country illegally is agreements between ICE and local jails around the country to hold people arrested on crimes past their release date so that ICE can look into their status. These are known as "detainers," but they've become increasingly unpopular among local governments, with many saying they risk legal action and that they shouldn't be doing the work of federal authorities.

The agency also arrests people the old-fashioned way, by tracking people down and showing up at their homes or workplaces.

But the amount of resources and staff limit their ability to make multiple large-scale arrests at a time.

What ICE has done

Last fiscal year, ICE's Enforcement and Removal Operations unit arrested over 158,500 immigrants in the country illegally, an 11% increase over the prior year and the highest number since 2014. The agency says 66% of those arrested are convicted criminals.

In May, ICE officers arrested 900 people during a three-week sting in California.

Although ICE arrests people a variety of ways, it's the larger enforcement operations such as a workplace sting that draw the most attention.

In Texas, ICE'S Homeland Security Investigations unit, which enforces immigration laws at workplaces, arrested 280 employees at a company in Allen in April, saying it was their biggest worksite operation in a decade.

"I think what people forget is these operations go on on a regular basis," said Art Acevedo, the police chief in Houston, one of the cities that might be targeted in a expected sweep this weekend.

What an ICE raid looks like

Authorities typically have a list of people they are targeting in any operation. They visit a targeted person's known addresses, usually a home or workplace, and seek to detain that person. They may ask family members, neighbors, co-workers or managers about the whereabouts of the person they want to arrest.

Authorities typically obtain an administrative warrant giving them permission to detain a person for violating immigration law.

ICE agents can arrest people they discover to be in the U.S. illegally while searching for people on their target list. People who answer ICE agents' questions about someone else sometimes end up arrested themselves.

In one case in Houston last year, a young father of five was arrested in the parking lot of his apartment building after ICE agents asked him about people who lived nearby, then demanded his identification and eventually detained him.

These "collateral" arrests can make up a large portion of the arrests in any ICE operation. In one December 2017 operation in northern Kentucky, just five of the 22 arrests ICE made were of people it originally targeted, according to agency documents released under the Freedom of Information Act.