Answer: send an undercover officer in, tap the phones
Explanation:
The first thing you want to do is gather physical evidence, buy a used car part and see if there are drugs inside. You also wanna stake out their shop and observe their movements and if you see any make sure you get it on video and put it in your report. Also go through their trash and try to find physical evidence. send in an wired undercover officer, and tap their phones and try to catch any suspicious phone calls. Once you have done all of these things. type up a warrant and get it signed by a judge.