A U.S. flag that turned up in Washington state in 2014 is believed to be the flag that was raised by firefighters above the site of the 9/11 attacks on the World Trade Center in New York.

The finding comes after a two-year investigation by the Everett Police Department, with assistance from forensic experts. The flag will be donated to the National September 11 Memorial & Museum.

Exactly how the flag wound up in Everett, a city about 30 miles north of Seattle, is a mystery. The flag disappeared from ground zero during the site cleanup. The police investigation began in November 2014, when a man dropped off a flag at an Everett fire station.

Former Everett Police Detective Jim Massingale told The Daily Herald “the flag is likely the same flag.”

The detectives’ investigation included DNA analysis, photographic comparisons and eyewitness identification.

(AP)