They did extradite the guy, and he's now in a California prison. Are you just not paying attention?
Yep, you're right. I was relying on memory rather than reading the entire article.
As an aside, I noted in other reports that the Chapmans had a local Mexican cop as an assist when they arrested the creep. So why were they arrested in the first place, and why weren't the charges dropped? It's all political and the Chapmans and American victims are held hostage.
The crime is that Mexico continuously refuses to aid the U.S. in tracking down those who try to escape the U.S. justice system by running away to Mexico. And then they expect us to treat Mexican national criminals in our country in accordance with Mexican law instead of U.S. law.