Different ways... One thing you have to understand before getting into these bloody details is how Cartels operate in our country. They bribe/threaten high ranking officers, politicians, or what have you to have their underlings act as brute force or informers, (police raids the rival's drugs, arrest them, kidnap them) they also pay little kids or young teens that sell stuff on the corners to act as "halcones"(they call them) or rats, snitches, whatever... Then they have these people give them information about their rivals. This also affects society (obviously) and that's why most people don't dare report crimes, security houses where they keep the drugs because eventually they find out through these channels.