As was explained in episode 801 " Indelible " , on the tenth anniversary of 9/11 , Ross confides to Lindsay Messer that he slept through the terrorist attacks of the day . He says he was out late at night at a club with friends and arrived home so late in the morning that when he finally awoke , the Pentagon was on fire and the World Trade Center was already destroyed . Ross then volunteered at Ground Zero in the subsequent cleanup and also help to rescue any survivors . Messer informed Ross that she too was working as part of the cleanup crew suggesting the pair possibly met before their employment at the crime lab
9/11
September 11 attacks
Adam Ross (CSI: NY)