An American flag that turned up in Washington state two years ago 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 Everett Police Department, with help from forensic experts, made the assessment after the flag turned up in 2014. The flag will be donated to the National September 11 Memorial & Museum.

Still, the mystery about how the flag turned up nearly 3,000 miles away from New York. The flag disappeared from Ground Zero during the site cleanup.

The police investigation began in November 2014 when a man, who identified himself as “Brian,” dropped off a flag in a plastic bag that he said was given to him by a widow of a 9/11 victim at an Everett fire station. According to Q13 Fox, the man said for some reason he thought the flag was from Ground Zero.

“This flag was turned in with a story. Reported to be the iconic flag raised at Ground Zero September 2001,” Everett Deputy Police Chief Mark St. Clair told Q13 Fox.

The detectives' investigation included DNA analysis, photographic comparisons and eyewitness identification. Washington State Patrol Crime Lab scientist Bill Schneck was tasked with figuring out whether the flag was from Ground Zero.

“Oh my gosh! I figured it was incredibly patriotic for one thing. Just to know I’m looking at something this important,” Schneck said.

He said that he began to examine the particles from the flag and compared with the dust particles captured from Ground Zero after the attack and during the cleanup. He also analyzed the original photograph.

“If you look at the original photograph from 9/11 you see a certain black electric tape holding two lines together and they had the same general profile so I knew then, well, this could be it,” he added.

Schneck said he analyzed his findings over and over again and is now certain that the flag was from Ground Zero.

He said he was invited to the ceremonies that are set to take place Sunday to remember the 15th anniversary of the terror attacks, but he declined saying that he’s no hero and that Americans should all remember the victims, first responders and the families involved in the attacks.

Everett police have asked the public to help find the man who dropped off the flag.

The Associated Press contributed to this report.

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