Colombia is winninh the war on drug cartels. As well as with the Farc's, so these all are based on the Darien now, who is the piece of land that connects Colombia and Panama.
As i was saying, if you want to enter the Darien, the panamian police won't let you in. You have to smuggle yourself in, as several young guys from europe and the states do, every year, just for the adventure....just go check it out on adventure travel forums...
Venezuela is way more dangerous than Colombia for the average, normal, traveller.