He said that although Costa Mesa's jail had an ICE agent screening arrestees for immigration violations for the last four years, there were "holes" in the system, especially when the agent was not on duty.
Between 2006 and 2009, ICE detained 1,225 arrestees in Costa Mesa for possible deportation. Of those, about a third have been for alleged felonies.
Costa Mesa was one of a few in Orange County cities in past years with an ICE agent posted to the city jail.
That changed in March, however, when ICE introduced its "Secure Communities" program in Orange County. Today, the ICE agent is gone, and now everyone who is arrested in the county and booked has their identity run through the Department of Homeland Security's database in addition to the usual Department of Justice and FBI databases.
If someone appears to be in the country illegally or has violated residency requirements, ICE may issue a detainer to keep him or her in custody.
"Our focus is on the Level 1 offenders, those who have convictions for the most violent or serious offenses," said ICE spokeswoman Virginia Kice. "We'll take a look at Level 2, Level 3 cases, and we'll make a decision about whether to follow up with enforcement action."
Since March, ICE has screened more than 20,000 suspects in Orange County and detained nearly 500, Kice said.
At this point, authorities can only check the immigration status of people arrested. However, Mansoor has pushed for more proactive techniques by police, such as checking the status of drivers pulled over who don't have a valid form of ID and can't have their names verified by police.
Last month the City Council declared Costa Mesa a "Rule of Law" city, a symbolic stance against illegal immigration.