Nightly News | April 21, 2012
>>> here in new york today investigators found something to aid them in a renewed search for a 6-year-old boy that disappeared 33 years ago. we have the latest in the search.
>> reporter: in the heart of new york city 's laid back and upscale soho district possible new clues. sources close to the investigation tell nbc news forensic teams cut off a section of drywall with the basement with what was described as a stain of interest. authorities don't know if it's significant but have taken the section to a lab for analysis. the latest search recaptured the city, the nation's attention. 33 years after he disappeared while working to his school bus stop.
>> i do remember when this happened 30-some years ago, and we just happened to be out this afternoon walking around. we noticed all the trucks. we walked up to see what was going on.
>> reporter: his disappearance rattled the country and changed the way the nation searches for missing children from his picture on million cartons to the amber alert and now experts say advances of technology that include the internet and social media .
>> we're disseminating missing child information instantly across america and around the world reaching millions of people, and as a result more missing children come home safely today than at any time in american history .
>> reporter: alan says in 1990 the recovery rate was 62%. today, the recovery rate is 97%. but alan says thousands of kids like etan are still missing, and the latest search also sends a strong message.
>> it is a very important message to the public and to law enforcement across this country that you don't close these files. the search continues.
>> reporter: back here at the scene, investigators describe their search as slow and methodical, a process of sift tl through debris and dirt. they finished up for the day. they estimate they're halfway down. lester.
>> michelle franzen .