Mike Horn said he will never forget the musky smell from the rubble pile of New York's World Trade Center.
"The smell, the odor, the sounds. It all set you back a little bit. It took your breath away for a moment," Horn said.
He was one of a team of dog handlers from the Las Vegas Police Department sent to search for survivors and remains of the dead after the twin towers collapsed 10 years ago.
Like the others, Horn found the whole experience "surreal."
When the dog teams were sent to New York on Sept. 21, 2001, Horn and Dak-the-Wak, then his partner dog, were given a dreaded task: finding bits of human remains in the massive rubble pile, still smoldering from 1,200-degree fires deep inside it.
"Even though you're emotional and you feel bad for everything, you put the resources together; you and the dog" go to work. He found some reward from the heart-wrenching job in the faces of survivors.
"You see the thankfulness of the fire department personnel who could be one of the brothers that you've helped out," he said.
Dak-the-Wak, like most of the search dogs, has since died, said Horn, 57, a canine trainer for the Las Vegas police. He now works with a new partner, Bucho.
Only Zorro, a jet-black Belgian malinois who was 3 years old in 2001, is still around. He finally retired after being transferred to the North Las Vegas Police Department.
His handler, Todd Fasulo, was a sergeant in the canine unit then and is now a captain with the Las Vegas department.
"The image you never get out of your brain is that 110 stories were down to three. You couldn't see the roads (between the buildings). You didn't see office equipment. You didn't see desks and chairs and phones and computers. All you saw was steel beams, rebar, soot and cement chunks," said Fasulo, 46, of Henderson.
"If we got a hit with the dogs, a big air horn would blow, and everything would stop on the pile and firemen ... would go up and attempt to recover any remains," he said.
Fasulo, Horn, Steve Junge and Eric Kerns and their dogs worked the 12-hour shifts in the effort to recover New York firemen, police and civilians who were lost in the towers' collapse.
Fasulo recalled "watching the firemen walking around with their heads down. It was like they were mentally, physically drained. But when they'd come over and see the dogs, it uplifted them, almost like a natural healing for them."
He said it was so important to all of the Federal Emergency Management Agency responders that they came together as a team. "Everybody was on the same page wanting the same thing."
Fasulo said that though they were given dust masks to wear, he lives with side effects from inhaling fine particulates. Last year, doctors diagnosed him with asthma that they think stems from rubble pile searches. "There are days I'll lose my breath sitting there having a normal conversation."
Another FEMA search volunteer who was at ground zero was Terry Wilferd, a captain with Henderson Fire Department.
Wilferd, 49, who volunteers as a paramedic with the Las Vegas police search-and-rescue team, said he was awestruck by the pile of pulverized concrete than had once been 220 acres of office space.
In the recovery effort, he found "partial victims" who could be identified as firefighters and police because of the uniforms they were wearing.
"Nothing compares to the scope of that. It's kind of hard to wrap your mind around it."
If there's anything he took away from the experience, Wilferd said it was "just the strength of the American spirit."
"As bad as it was and as many people that it impacted, Americans always come together and they perform outstanding."
He said he is satisfied to know that they did something for the families to help them reach closure.
"Just remember the human toll," he said. "We can always rebuild the building. We can always paint a structure and sweep away the mess but you can't replace the people. So just remember the human toll."
Contact reporter Keith Rogers at firstname.lastname@example.org or 702-383-0308.