Don't ever do it "on your own". Don't ever contact local police.
Contact your embassy / consulate, explain everything truthfully and your suspicions. You may or may not be charged (you've already been an idiot and deserve whatever you get). But at least, you'll (probably) be getting if from your own justice system which will be better for most citizens of most countries.
Most citizens of most countries, yes, but in this case he seems to have been a US citizen. While there are many wonderful things about the US, mercy for drug smugglers is not among them, particularly compared to Argentina or Ecuador.
Contact your embassy / consulate, explain everything truthfully and your suspicions. You may or may not be charged (you've already been an idiot and deserve whatever you get). But at least, you'll (probably) be getting if from your own justice system which will be better for most citizens of most countries.