NYPD investigators were doing forensic tests -- including those for possible DNA evidence -- of the two white flags placed atop the Brooklyn Bridge earlier this week as efforts continued to find those responsible for the caper, law enforcement officials said Thursday.
Potential DNA evidence was taken from the lights atop the two bridge towers but results were not yet available, said one law enforcement official. The flags, about 20 feet by 11 feet, also were examined, but were thought to be less likely to yield DNA material, said the source, who didn't want to be identified.
The NYPD was jolted early Tuesday when the two white flags, which appeared to be bleached American flags, were discovered atop the bridge towers. Large spotlights on the towers had been covered by aluminum pads secured with ties. No person or group has claimed responsibility and police think the action could turn out to be some kind of stunt or artistic statement.
Normally, American flags fly on the towers and had been doing so the evening of July 21. Though police said the flag switch wasn't terrorism-related, the fact that people scaled the two towers on one of the city's most important landmarks raised questions about the adequacy of security at the bridge, which is a terror target.
"Needless to say, whatever the motive was, it is a matter of concern. I am not happy," NYPD Commissioner William Bratton said Tuesday.
Detectives with the NYPD intelligence and detective bureaus were sorting through numerous leads and reviewing surveillance videos. So far, police said the video shows a group of four or five young men entering the bridge walkway from the Manhattan side and carrying what appeared to be a skateboard. Video from various subway stops also was being examined, said the source.
Detectives have been combing social media and Internet postings to see if any other events, such as the July 20th anniversary of the first lunar landing in 1969, might provide a clue.
"They are thinking outside of the box," an NYPD official said of the investigation.