An unpaid intern to Sen. Robert Menendez, D-N.J., was a registered sex offender and undocumented immigrant and is now facing deportation, a DHS official confirmed Wednesday to ABC News.

The intern, 18 year-old Luis Abrahan Sanchez Zavaleta from Peru, who worked in a New Jersey office for Menendez, was arrested on December 6 th. The news was first reported by the Associated Press.

The senator's office was informed Monday of the arrest and the senator was informed today, Menendez said. The Senator defended his office's action today, emphasizing that the intern applied, was recommended and vetted by his school for the internship, not the Senators office.

"We asked status of all of those college interns, nothing didn't indicate anything about his status and we certainly wouldn't have known through any background checks since he is a minor about any sex offender status," Menendez said on MSNBC this afternoon.

Once Menendez's office was informed of the arrest, the Senator's New Jersey staff director let the intern go from the program.

"He's an unpaid college intern so it's not like he's a staff paid person," Menendez said, "There is no way we could know about his status. We ask about status…there is no way we could know about any allegation as a juvenile about what his background would be in terms of any criminality."

Menendez is a advocate for immigration reform and noted today that this does underscore the urgency of such reform.

"I can't know who is here to pursue the America dream versus who is here to do it damage if I can't get people to come forth out of the shadows, go through a criminal background check and determine who is here to pursue the dream and make sure those who are here and who have criminal backgrounds ultimately get deported," he told MSNBC today.