Teen Sneaks Past Security, Climbs Atop 1 World Trade Center He managed to reach the spire of the tallest building in the Western Hemisphere.

March 20, 2014 -- A New Jersey teen managed to breach security in middle of the night and climb the spire of 1 World Trade Center to take photos, authorities said.

The teen was identified in court papers as Justin Casquejo, who told police, "I was walking around the construction site and figured out how to access the Freedom Tower rooftop."

Casquejo, 16, was arrested for trespassing at 6 a.m. Sunday morning after a construction supervisor spotted him coming down from the 1,776-foot building, according to Port Authority police.

WATCH: Thrill-Seeking Teen Breaches Security at World Trade Center and Gets to Top

A law enforcement source told ABC News that, upon review, security cameras showed "faint" glimpses of the teen, who entered the perimeter near Church and Vescey streets in lower Manhattan.

The official said it appeared Casquejo was "trying to be stealthy and avoid detection" -- although a red blinking light from his GoPro camera was visible.

To reach the antenna of the building -- the tallest in the Western Hemisphere -- the teen squeezed through what officials tell ABC News was a "12 by 12-inch hole."

Law enforcement said the teen "admitted" what he did and explained he took the stairs to 20th floor, an elevator to the 99th floor and then went to the spire.

Exterior walls are complete so there wasn't an immediate risk of Casquejo falling off the building.

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The security at 1 World Trade Center -- which was previously believed to be impenetrable -- is now under investigation.