The following script is from "Sniffing For Bombs" which aired on April 21, 2013 and was rebroadcast on July 21, 2013. Lara Logan is the correspondent. Max McClellan and Reuben Heyman-Kantor, producers.
When the bombs went off at the Boston Marathon this spring, highly trained dogs were rushed to the scene to search for more explosives. Boston police said dogs swept the streets in the morning and a second time just an hour before the first marathoners crossed the finish line. It's now known that the bombers planted their devices well after the dogs finished sweeping the area.
Since 9/11, dogs have been used more than ever because nothing has proven more effective against hidden bombs than the nose of a working dog. The best of them serve with U.S. Special Operations and they're in a league of their own.
It's nearly impossible to get anyone to talk about them publicly because much of what they do is classified, but we were able to talk to the people who train them for this story. And, as we first reported in April, we took the opportunity to ask about what might have happened in Boston while getting a rare glimpse inside the secretive world of America's most elite dogs.
Green Beret Chris Corbin and his dog, Ax, are at 14,000 feet in the skies over North Carolina.
They're about to test a new harness that America's best soldiers will use to jump into combat. But it's not for Corbin -- it's for Ax.
As they free-fall for nearly 10,000 feet at 125 miles an hour, Ax is wrapped in Corbin's arms. They've been to war together, nearly died together, and they never like to be too far apart.
Lara Logan: Do you think he enjoyed it?
Chris Corbin: He just wants to do whatever I'm doing, he doesn't care what it is.
Lara Logan: You've said that these dogs feel like they're invincible?
Chris Corbin: Absolutely.
Lara Logan: What makes you say that?
Chris Corbin: We don't train them to fail.
Sergeant First Class Corbin is a dog handler with 7th Special Forces Group and he and 6-year-old Ax have been a team for three years. They deployed to Helmand in southern Afghanistan at a time when more Americans were dying there than any other place in the country. Corbin and Ax's job was to lead their unit through a battlefield littered with hidden bombs.
Chris Corbin: We walked in front. We cleared the pass for everyone to move through.
Lara Logan: You say it so easily. "I walked out front." Like it's nothing. But what does that actually mean when you're the one walking out front?
Chris Corbin: You are the one risking, I hate to say the most, but yeah, you're out front. I'm the one who makes it safe or announces it as safe for everyone else to walk behind.
Lara Logan: What's your level of trust in your dog?
Chris Corbin: It has to be this perfect trust.
Perfect trust that begins with trainers like former Navy SEAL Mike Ritland. He's one of just a handful of people in this country who finds and trains these dogs for Special Operations and top tier units in the FBI and police departments across the U.S.
Lara Logan: What can these dogs do on the streets of America?