President-elect Donald Trump promised to deport anywhere from two to three million undocumented immigrants.
Saying that is one thing but following through could be challenging - especially since some police departments in large cities, such as the LAPD, have said they will not help the federal government carry out deportations.
One tool that Trump might use is a database of alleged gang members, which includes some people who are not in the country legally. However, some say the database is not without its problems.
For more, A Martinez spoke with Ali Winston. He's written about the so-called CalGang database for The Intercept.