to a couple of friends in honolulu, investigators with the state attorney general's cold case unit. >> i asked them to see if they can find anything else that we may have missed. >> and they did indeed find something using what was breakthrough science for that time, early 2009. cold case investigators extracted touch dna from sandra's shirt and bra. chief perry called larry with the news. >> and he said, they've got something. they rescanned her clothes and they found two -- how did he put it? two microscopic particles of a male origin. >> sometimes it is what you find and sometimes it is what you don't. coming up -- brrp. >> you know, going through the calendar way found really interesting is that it is pretty detailed from january 1st all the way up until the 24th. >> but on the morning of sandra's murder -- >> you've got nothing. >> when "dateline" continues. n e is changing him...