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Three skydivers spent about four hours atop the World Trade Center’s signature skyscraper before parachuting off it, they said Tuesday in detailing a stunt that raised questions about security and left them facing felony charges.

James Brady, Marko Markovich and Andrew Rossig acknowledge making the Sept. 30 leap from the as-yet-unfinished 1 World Trade Center, the nation’s tallest building and one of its most security-conscious. But they pleaded not guilty Tuesday to burglary, reckless endangerment and other charges.

Authorities say the escapade audaciously broke laws specifically prohibiting such jumps. The jumpers portray it as a careful, middle-of-the-night plunge by experienced skydivers over deserted streets.

“We didn’t endanger anyone,” Rossig said as he left court.

The trio has garnered support from two Sept. 11 victims’ relatives, who say the skydivers spotlighted security lapses at the trade center site. The site’s owner, the Port Authority of New York and New Jersey, insists it’s well-protected, while acknowledging that daredevils have prompted some security changes recently.

The parachutists were arrested last month, shortly after a teenage thrill-seeker was accused of climbing to the top of the 1,776-foot-tower.

Brady, an ironworker who had worked at the trade center, and Markovich, a skydiving instructor, initially denied involvement, according to prosecution court papers released Tuesday. But the filing says an accused accomplice on the ground, Kyle Hartwell, told police that Markovich, Brady and another person were involved — and that Brady provided access to the building and stashed parachutes there beforehand.

The parachutists, like the accused teenage climber, say they simply walked through a hole in the site’s fence. The jumpers say they walked into the building — which had no door at the time — climbed stairs to the roof and enjoyed “magnificent views” for four hours before the 3 a.m. plunge, encountering no security guards.

Police Commissioner William Bratton last month called the stunt “a desecration of that site.” He said it invoked memories of those who jumped from the burning twin towers on Sept. 11.

But Sally Regenhard and Jim Riches, who both lost firefighter sons in the attacks and have criticized aspects of the city’s preparedness and response, said the parachutists’ leap didn’t offend them.

“They may have indeed performed a public service by exposing the lack of security, accountability and responsibility that still exists at the WTC site,” Riches and Regenhard wrote in letters asking a judge to be lenient with the parachutists.

Rossig’s lawyer, Timothy Parlatore, said he and his client walked around the site and spotted gaps in the fence just this week.

Port Authority spokesman Andrew Hayes said that since the stunts came to light, “there have been changes made that include physical strengthening at the site, as well as operational and policy changes.” He wouldn’t give details and declined to comment on the skydivers’ specific claims.

The parachutists and Hartwell, who also pleaded not guilty Tuesday, face a felony burglary charge that entails being in a building illegally with an intent to commit another crime — breaking a 2008 city law against scaling or parachuting off tall buildings.

(AP)