>Despite the publicity generated by Porteous's book and the 2011 television documentary, the FBI is standing by its position that Christiansen cannot be considered a prime suspect.[50][168] It cites a poor match to eyewitness physical descriptions, a level of skydiving expertise above that predicted by their suspect profile, and an absence of direct incriminating evidence.[201]

https://en.wikipedia.org/wiki/D._B._Cooper#Kenneth_Christian...

I do like the more recent evidence from the tie; it contains titanium shavings or fragments.

https://www.seattletimes.com/seattle-news/northwest/does-tha...