NEW YORK – Investigators are running license plate numbers, scouring social media, examining cellphone transmissions and collecting DNA as part of their investigation into who climbed the Brooklyn Bridge in the middle of the night to plant two bleached-white American flags there, NBC News has learned.

[…]  The high-quality flags, measuring about 11 feet about 20 feet, were made out of white linen, and the stars were individually stitched on, according to a senior law enforcement official. There were also large aluminum pans affixed over the bridge lights that normally illuminate the flags, secured with zip ties.
The NYPD has obtained a small amount of DNA from the flags or tin pans that investigators are now seeking to test, a senior NYPD official tells NBC News. They’re also looking at cellphone transmissions from the bridge in the time frame that the flags were swapped.  (read more)