Editing D. B. Cooper (section)

===Clip-on necktie===
FBI agents found a black clip-on necktie in seat 18-E, where Cooper had been seated. Attached to the tie was a gold tie-clip with a circular mother-of-pearl setting in the center of the clip.{{r|vault_64|page=124|quote="On the seat numbered 18E a black clip-on tie was observed. This black tie contained a tie clasp, yellow gold in color. with a white pearl circular stone in the center." }} The FBI determined the tie had been sold exclusively at [[JCPenney]] department stores, but had been discontinued in 1968.<ref>{{cite report|title= Letter to Director of FBI|date= February 24, 1972|url= https://vault.fbi.gov/D-B-Cooper%20/D.B.%20Cooper%20Part%2022/view|publisher= Federal Bureau of Investigation|page= 355|access-date= February 8, 2023|archive-date= March 6, 2023|archive-url= https://web.archive.org/web/20230306114245/https://vault.fbi.gov/D-B-Cooper%20/D.B.%20Cooper%20Part%2022/view|url-status= live}}</ref>

By late 2007, the FBI had built a partial [[DNA]] profile from samples found on Cooper's tie in 2001.<ref name=HelpSolve/> However, the FBI also acknowledged no evidence linked Cooper to the source of the DNA sample. FBI Special Agent Fred Gutt said, "The tie had two small DNA samples, and one large sample&nbsp;... it's difficult to draw firm conclusions from these samples."<ref name=NotMatch>{{cite news |last=Cloherty |first= Jack |date=August 9, 2011 |title= D.B. Cooper DNA results: "not a match" |url=https://abcnews.go.com/US/db-cooper-dna-results-match/story?id=14258726 |publisher= ABCNews.com|archive-url=https://web.archive.org/web/20200428114122/https://abcnews.go.com/US/db-cooper-dna-results-match/story?id=14258726 |archive-date=April 28, 2020 |access-date=August 9, 2011}}</ref> The FBI also made public a file of previously unreleased evidence, including Cooper's airplane ticket,<ref name="King5">{{cite news |last=Ingalls |first=Chris |date=November 1, 2007 |title=Investigators: F.B.I. unveils new evidence in D.B. Cooper case |work=[[KING-TV|King 5]] |url=http://www.king5.com/localnews/stories/NW_110107INK_cooper_chute_KS.1cbb87e02.html |access-date=March 11, 2008 |archive-url=https://web.archive.org/web/20080105030027/http://www.king5.com/localnews/stories/NW_110107INK_cooper_chute_KS.1cbb87e02.html |archive-date=January 5, 2008}}</ref> composite sketches, fact sheets, and posted a request for information about Cooper's identification.<ref name="FBIVault7" /><ref name="HelpSolve" /><ref>{{cite web | title = Interview with lead FBI Investigator Larry Carr | publisher = Steven Rinehart | date = February 2, 2008 | url = http://www.stevenrinehart.com/uploads/LarryCarrInterview.mp3 | access-date = February 2, 2008 | archive-date = February 29, 2008 | archive-url = https://web.archive.org/web/20080229090209/http://www.stevenrinehart.com/uploads/LarryCarrInterview.mp3 | url-status = dead }}</ref>

In March 2009, a group of "citizen sleuths" using GPS, satellite imagery, and other technologies unavailable in 1971,<ref name="isodbc" /> began reinvestigating components of the case. Known as the Cooper Research Team (CRT),<ref name="CitizenSleuths">{{cite web |title=Citizen Sleuths analyze the D.B. Cooper case |url=http://www.citizensleuths.com/ |url-status=live |archive-url=https://web.archive.org/web/20111125233157/http://www.citizensleuths.com/ |archive-date=November 25, 2011 |access-date=December 7, 2011 |publisher=citizensleuths.com}}</ref> the group included [[paleontologist]] Tom Kaye from the [[Burke Museum of Natural History and Culture]] in Seattle, scientific illustrator Carol Abraczinskas, [[computer scientist]] Sean Christo, and [[metallurgist]] Alan Stone. Although the CRT obtained little new information about the buried ransom money or Cooper's landing zone, they found, analyzed, and identified hundreds of organic and metallic particles on Cooper's tie.

Using [[electron microscopy]], the CRT identified ''[[Lycopodium]]'' spores, the source of which was likely pharmaceutical. The team also found minute particles of unalloyed [[titanium]] on the tie, along with particles of [[bismuth]], [[antimony]], [[cerium]], [[strontium sulfide]], [[Aluminium|aluminum]], and titanium-antimony alloys.<ref name="CitizenSleuths" /> The metal and [[rare earth mineral|rare-earth]] particles suggested Cooper may have worked for Boeing<ref name=":0">{{Cite web |last=Ingalls |first=Chris |date=January 13, 2017 |title=Scientists say they may have new evidence in D.B. Cooper case |url=https://www.usatoday.com/story/news/nation-now/2017/01/13/scientists-say-they-may-have-new-evidence-db-cooper-case/96575858/ |url-status=live |archive-url=https://web.archive.org/web/20170530125909/https://www.usatoday.com/story/news/nation-now/2017/01/13/scientists-say-they-may-have-new-evidence-db-cooper-case/96575858/ |archive-date=May 30, 2017 |access-date=January 16, 2017 |website=USA Today}}</ref><ref name=":1">{{Cite news |date=January 13, 2017 |title=New evidence: Was DB Cooper a Boeing employee? |work=KING-5 |url=http://www.king5.com/news/crime/new-evidence-was-db-cooper-boeing-employee/385924766 |url-status=dead |access-date=January 16, 2017 |archive-url=https://web.archive.org/web/20170115013533/http://www.king5.com/news/crime/new-evidence-was-db-cooper-boeing-employee/385924766 |archive-date=January 15, 2017}}</ref> or another aeronautical engineering company, at a chemical manufacturing plant, or at a metal fabrication and production facility.<ref>{{Cite news |last=Johnson |first=Gene |date=November 23, 2011 |title=40 years later, DB Cooper's identity a mystery |work=KGW |agency=Associated Press |url=http://www.kgw.com/news/local/40-years-later-DB-Coopers-identity-a-mystery--134407308.html |url-status=dead |access-date=November 23, 2011 |archive-url=https://web.archive.org/web/20130921054223/http://www.kgw.com/news/local/40-years-later-DB-Coopers-identity-a-mystery--134407308.html |archive-date=September 21, 2013}}</ref>

The material with the most significance, explained Kaye, was the unalloyed [[titanium]]. During the 1970s, the use of pure titanium was rare and would only be used in aircraft fabrication facilities, or at chemical companies combining titanium and aluminum to store extremely corrosive substances.<ref>{{cite web |last=Ingalls |first=C |date=November 23, 2011 |title=40 years later, new evidence unveiled in DB Cooper case |work=KING king5.com |url=http://www.king5.com/news/investigators/40-years-after-the-crime-new-evidence-unveiled-in-DB-Cooper-case-134417003.html |archive-url=https://web.archive.org/web/20130909113338/http://www.king5.com/news/investigators/40-years-after-the-crime-new-evidence-unveiled-in-DB-Cooper-case-134417003.html |archive-date=September 9, 2013 |access-date=May 29, 2013 |publisher=King5.com}}</ref> The cerium and strontium sulfide were used by [[Boeing]]'s [[Boeing 2707|supersonic transport development project]], and by Portland factories in which [[cathode-ray tube]]s were manufactured, such as [[Teledyne]] and [[Tektronix]].<ref name=":3">{{Cite web |last=Williams |first=Kale |date=January 17, 2017 |title=D.B. Cooper could have worked at Portland-area tech firm, scientists say |url=https://www.oregonlive.com/portland/2017/01/latest_db_cooper_theory_skyjac.html |url-status=live |archive-url=https://web.archive.org/web/20201111190549/https://www.oregonlive.com/portland/2017/01/latest_db_cooper_theory_skyjac.html |archive-date=November 11, 2020 |access-date=December 11, 2020 |website=The Oregonian}}</ref> Cooper researcher Eric Ulis has speculated that the titanium-antimony alloys are linked to Rem-Cru Titanium Inc., a metals manufacturer and Boeing contractor.<ref name="petersen-king">{{Cite web | url=https://www.king5.com/article/news/investigations/tiny-particles-db-cooper-mystery/281-17ca7f6e-2f06-4997-a4ab-7fadde3abe13 | publisher=KING 5 | title=3 particles, 1 possible clue found in D.B. Cooper mystery | date=July 20, 2022 | access-date=December 23, 2022 |archive-date=October 29, 2022 | archive-url=https://web.archive.org/web/20221029000832/https://www.king5.com/article/news/investigations/tiny-particles-db-cooper-mystery/281-17ca7f6e-2f06-4997-a4ab-7fadde3abe13 | url-status=live}}</ref>