does anyone know if the method Columbo used on the ship in Troubled Waters to obtain prints was legit?...I mean obviously the process would yield prints, or they wouldn't have used it....but did he actually do it correctly?
and would a magnifying glass actually confirm prints? I could probably Google it....but if anyone "in the know" can elaborate that'd be cool

Sure its a trick that he learned in the Hollenbeck Division from an old sergeant when he first started out.