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They are described as the ‘worst of the worst.’

Before dawn in northern Virginia, after days of heavy surveillance, the Immigrations and Customs Enforcement Fugitive Operation Team is taking a 42-year-old man from el Salvador into custody.

The man, a green card holder, is eligible for deportation because he was convicted of sexually assaulting a minor.  FOX News is told the man’s parole officer provided homeland security with the lead.

“We don't do sweeps, we don't do raids.  We are looking for specific individuals who have been convicted of crimes who are not supposed to be here, do not lawfully reside in US,”  Henry Lucero told FOX News on an exclusive ride along with Fugitive Operation Team members.

The team is briefed at 4 a.m. on its targets, though it has taken weeks of surveillance and tracking down tips to reach this point.  Once on the road, we learn that in each case, the targets either ignored an order to leave the country or ignored the terms of their visas.

"[The] next person we're looking for is from Morocco, 22 yrs old,”  Lucero says inside the Homeland Security Vehicle.  “He's been convicted of drug possession and burglary...”

Lucero says the team expects to encounter the suspect’s family members who have over stayed visas at the house.

The Fugitive Operation Program began in 2003 and it has changed over the years.  With limited resources, agents says the focus is picking up the worst of the worst. One-hundred and four teams from across the US made 35 thousand fugitive arrests last year.  In nearly 90 percent of the cases, the fugitives were convicted of crimes.  That's a dramatic jump from seven years ago when the program started with less than  two thousand pick-ups.

On this morning, five men are processed and their digital fingerprints are taken.  The data is sent to larger databases, including the FBI, to check for other charges.

One target, a fugitive who has an outstanding warrant in South Carolina for assault with intent to kill, slips through the net.

“We have a team currently back there doing work we started 4 a.m.  It's now 11 [am] but our job is not over,” Lucero says. “They're back there chasing down leads, interviewing neighbors, looking for forwarding address, getting phone  numbers associated with this individual. We won’t stop until we find this individual.”

Agents told FOX News there are only five immigration judge in the Washington, D.C. area, so picking these criminals up is one thing.  But it can still take at least three months to deport them. In some cases, when the individual is not a convicted criminal and not held, the first court appearance can be up to a year away.