Here are the 14 that I deleted, edit summary in italics (excludes 8 ships & aircraft - see Ships?):
 Fernando Bengoechea [] known victim of the 2004 Indian Ocean earthquake tsunami
 Sneha Anne Philip [] has been officially declared a 9/11 victim - http://www.nytimes.com/2008/02/02/nyregion/02dead.html
 Upali Wijewardena [] not mysterious, plane wreckage found same year - http://www.forachange.co.uk/browse/2264.html
 Alexander Grothendieck [] see Recluse#Recluses listing, and Category:Hermits
 Andrew Fluegelman [] see Category:Inventors_who_committed_suicide
 Tommy O'Connor [] article is for a different person; fujitive, not mysterious; no s; not mentioned in The Front Page article
 Airship Italia [] not mysterious, North Pole airship crash
 Charles White Whittlesey [] see Category:Military_personnel_who_committed_suicide
 Jüri Vilms [] no mention of "disappearance" or "missing" in the Jüri Vilms article
 John Franklin & crew [] not mysterious - see Franklin's lost expedition
 Leopold Frankenberger [] no mention of this in the article; see also Talk:Leopold Frankenberger
 Laozi [] article says "Traditional accounts state ... he ventured west to live as a hermit ... at the age of 160"
 Spartacus [] body not found but known to have died in battle - http://penelope.uchicago.edu/Thayer/E/Roman/Texts/Appian/Civil_Wars/1*.html#120
 K'inich K'an Joy Chitam II [] "captured by the Tonina in 711 and was possibly executed by their leader"