Several teams of federal agents from here and across the country are hitting the streets of Houston searching for fugitive illegal immigrants.

The hunt in Houston began a few hours before sunrise on Tuesday.

Half an hour into their operation, Immigration Customs Enforcement agents catch a bad guy.

ICE officers say the man they arrested had committed several violent crimes and assaulted his former wife.

A woman, who agents identified as his current wife, walked away when 11 News tried to ask her about her husband’s citizenship status.

ICE officers say there are an estimated 38,000 known illegal immigrants with criminal histories in Houston.

It is an astonishing number and catching bad guys, officials say, is not easy.

They say fugitives on the run constantly change their addresses and work locations.

Catching the fugitive immigrants takes hours of surveillance and planning too.

At another location, agents look for yet another fugitive.

They didn’t catch the man they were looking for, but half an hour later an illegal immigrant from Columbia is in cuffs. Another from Nigeria is about to get deported.

Once the fugitive illegal immigrants are arrested they are brought to a  processing center in north Houston. 

Most of them have been there before.

This time though, they won’t be released.

What happens inside the facility?

11 News got a rare behind the scenes look at how agents identify criminals.

Agents use computerized fingerprinting and record checks in identifying the worst of the worst.

Greg Palmore is with ICE Houston. “It’s important for us to remove a lot of these individuals particularly because particularly because they have committed crimes.  They are fugitives they are abconders. There are many names for them.  But the bottom line is they don’t have a valid status in the United States.”

That was exactly the case with Juan Quintero. He’s the illegal immigrant convicted of killing HPD officer Rodney Johnson during a traffic stop nearly two years ago.

Timoteo Rios is blamed for stabbing Tina Davila during an attempted carjacking in April.

The list goes on.

Agents are hoping to get people like Quintero and Rios off the streets before they strike again.

With thousands of fugitive immigrants on the streets here, the odds of catching them are not good, but agents say this operation is a start.