Just over the U.S border in Ciudad Juarez, Mexico, a dozen more people were killed this weekend continuing a disturbing trend. Last year there were 1,600 killings. That's not just a lot of lives destroyed, that's more than double the murder rate in the most violent city in the U.S.

An increase in police presence in Juarez has stemmed some of the killings but police have determined that thousands of the weapons they've now seized were smuggled into Mexico from the United States. Since Mexico has strict gun control laws, its government demanded the U.S. reduce the flow of firearms across the border. No easy task.

While the U.S. and Mexican authorities are now sharing information and technology, tracking the sale and movement of guns can prove very tricky as no national registry of firearms exists in the United States.

"Sometimes you hit a homerun and the bad guy's the one who went in and buy the gun. Other times, you go and you talk to three different people. You know, 'I sold it to so-and-so.' 'So-and-so says I sold it to this guy.' And this guy says, 'I don't remember what I did with it. I traded somebody a TV for it. I don't know.' And then it's just -- that's it. It just dies." ATF ballistics expert

"The vast majority of [gun sellers] have a lot of integrity and they keep the records that they should, and they're a partner with us in our gun-trafficking investigations. But there are a couple, you know, 2 percent or 3 percent, perhaps, that aren't compliant with the rules and the regulations." Kenneth Melson, ATF Acting Director

"Two propositions cannot both be true at the same time. That is that relying on federally licensed dealers to stop gunrunning and record levels of gunrunning existing at the same time, they both can't be true. They're mutually exclusive. Either the dealer system works or it doesn't. The evidence is that it does not." Tom Diaz, Violence Policy Center

1. How easy is it to buy guns in the United States? Where can you buy them?

2. What amendment guarantees the "right to bear arms"?

1. The authorities have concluded that most of the guns used in Mexico come from the United States; do you think that the U.S. has responsibility for these guns? Why or why not?

2. In your opinion do you agree with "the right to bear arms"? Why or why not?

3. Does the fact that Mexican drug gangs are using U.S. guns change your opinion about gun laws in the United States? Why or why not?

4. Why do different people have different attitudes towards guns?