BOB ABERNETHY, anchor: Now, the story of a truly remarkable and extraordinarily brave man. He is a Cambodian, orphaned as a child. Then, before he was a teenager, he became a soldier. Now, as Lucky Severson reports, he is devoting his life -- and risking it, almost daily -- compensating for, atoning for, the harm he once did.
AKI RA (Former Khmer Rouge Soldier, walking through a minefield): You walk same step, many step, be careful.
LUCKY SEVERSON: When friends tell Aki Ra to be careful of land mines along the way, they're not speaking of the political kind. They're referring to the kind that blow up people and animals, the kind hidden in the bush where Aki is walking. It's what he does, day after day, for no pay. He defuses and clears land mines so they won't kill or maim any more of his countrymen.
Mr. RA (poking at half-buried mine with shovel): They're very difficult to see buried in the grass.
SEVERSON: On this day, he pretty much knows where they are; usually he remembers only a field or a particular area. After all, he laid mines for over a decade.
(to Mr. Ra): You want to clear those you laid yourself?
Mr. RA: Yeah.
SEVERSON (to Mr. Ra): How many, do you think?
Mr. RA: Many, many thousand.
SEVERSON (to Mr. Ra): How many would you lay in a day?
Mr. RA: One day, sometimes we lay 50 or 100 mines a day.
SEVERSON (to Mr. Ra): And you did that day after day?
Mr. RA: Yeah.
(picking up a rifle): When I am twelve years old, I use this small one.
SEVERSON: He was a soldier then, but only a child. It was during Cambodia's bloody revolution that raged during the early 1970s, when one of the world's cruelest despots, named Pol Pot, ordered his forces to commit genocide on his own people. Almost a quarter of the population were murdered or died, and among the two million victims were Aki's mom and dad. He was only nine when he was conscripted to become a child soldier for the Khmer Rouge.
Mr. RA: We don't see at nighttime, we just shoot. We kill many many enemy and shoot machine gun when they come a lot, and shoot. We don't know how many dead, how many injured.
SEVERSON: Aki turned out to be a very brave soldier in the bloody war that erupted between the Khmer Rouge and their age-old enemy next door, the Vietnamese -- first fighting against the Vietnamese until he was captured, and then for them. For both sides, he planted thousands of deadly land mines that can have a lifespan of 75 to 100 years. At the time, he says, he was a soldier doing his duty. Later, he realized what he had done and determined it was his moral obligation to undo it.
(to Mr. Ra): You were too young to know better?
Mr. RA: I understand now I'm big, not same as before, and I know it's not good that I did before in the war, but now I try to do everything good for my country.
SEVERSON: The people of his country are hurting, still paying the price of war. Just about every day, someone steps on a land mine. Last year, an average of three people were killed or maimed every 24 hours.
Ray Worner is a land mine expert.
RAY WORNER (Project Advisor, Cambodian Mine UXO Victim Info System): We're looking, total, since our records began from 1979 to the present, around 60,000 people so far have been killed and injured by land mines and unexploded ordinance.
SEVERSON: More than half the victims are children, most often young boys.
Mr. WORNER: They'll throw rocks and land mines, they will throw them against trees to watch them explode. They'll play with them a lot more than anybody else. So boys particularly are very, very vulnerable.
Mr. RA: The village people say here that a lot of people come to dig the ground to grow the banana and then blow up land mines -- some killed, some injured -- many times here.
SEVERSON: It's estimated that 1,300 square miles of Cambodia are strewn with as many as 10 million land mines.
This school, surrounded by warning signs, sits in the middle of a parcel of land, still littered with mines.
There are international humanitarian agencies methodically clearing the country of mines, but it's very tedious, slow going, and at the current pace, it will take many decades. These agencies discourage impatient Cambodians from clearing the land themselves, because so many become casualties.