Justin Gaertner, retired Marine, joins H.E.R.O. Corps

(WJLA) - A marine who lost his legs while trying to protect lives in Afghanistan now has a new mission in life - to hunt child predators and rescue children in danger.

Retired Cpl. Justin Gaertner is part of the new group called the H.E.R.O. Child-Rescue Corps. He lost both of his legs in Afghanistan when he was just 21 years old.

"When I was sweeping for helicopter landing zones to get the guys out of there is when I stepped on an IED," he says. "I thought my life was over. I thought I would never walk again."

But Gaertner, now 24, did more than just walk again - he became a gold medal athlete. And now instead of tracking IED's, he is tracking child sex predators through H.E.R.O. Corps. The inaugural class was sworn in Friday morning.

“Some people get upset when I call child sexual predators terrorists, but in my eyes, you are raping a child in my country, you are a terrorist,” he says.

Gaertner will use his military skills to track online pedophiles and to identify the countless children in pornographic images and videos.

“The best part about it is finding the children and saving kids’ lives.”

Gaertner's service dog Gunner will join him in his fight.

“If someone is not there to help me, he is. He will. That is why I got him a new vest, so I can load all my hard drives and stuff.”

Gaertner joined the H.E.R.O. Corps because of his little sister.

"She thinks I am the coolest guy in the world and I am her hero and I want to continue being her hero," he says.