D. B. Cooper
https://en.wikipedia.org/wiki/D._B._Cooper#Physical_evidence
https://www.fbi.gov/history/famous-cases/db-cooper-hijacking

The Human Timebomb
https://unsolved.com/gallery/human-time-bomb/
http://unsolvedmysteries.wikia.com/wiki/Harvey_McCloud

Rocco Perri
https://en.wikipedia.org/wiki/Rocco_Perri
https://www.thespec.com/community-story/6870542-april-23-1944-hamilton-mobster-rocco-perri-disappears/

Lord Lucan
https://en.wikipedia.org/wiki/John_Bingham,_7th_Earl_of_Lucan#Ultimate_fate_and_reported_sightings
http://www.telegraph.co.uk/tv/0/happened-lord-lucan-still-alive-likely-theories/
Victor Gerena
https://en.wikipedia.org/wiki/V%C3%ADctor_Manuel_Gerena
https://unsolved.com/gallery/victor-gerena/

The Gardner Museum Robbers
https://en.wikipedia.org/wiki/Isabella_Stewart_Gardner_Museum_theft#Loss_of_DNA_evidence
https://www.npr.org/sections/thetwo-way/2017/12/27/573759593/got-the-scoop-on-the-gardner-museum-art-heist-you-have-4-days-to-earn-10-million

Szilveszter Matuska
https://en.wikipedia.org/wiki/Szilveszter_Matuska
http://murderpedia.org/male.M/m/matuschka.htm

Matteo Messina Denaro
https://en.wikipedia.org/wiki/Matteo_Messina_Denaro#Mafia_background
http://www.independent.co.uk/news/world/europe/italian-police-seize-mafia-bosss-assets-worth-millions-of-euros-is-this-the-end-of-the-line-for-9926827.html

The Zodiac Killer
https://en.wikipedia.org/wiki/Zodiac_Killer
http://www.history.com/news/the-zodiac-killer-a-timeline

Aribert Heim
https://en.wikipedia.org/wiki/Aribert_Heim#Mauthausen_concentration_camp
http://www.telegraph.co.uk/news/worldnews/europe/germany/4524580/Son-of-Dr-Death-Aribert-Heim-to-escape-charges-for-concealing-Nazi-fathers-existence.html