I was at a location where a drug search warrant was being executed. After a Terry frisk, they found no narcotics on me. My car was parked in the driveway and they searched it and found half of an alprazolam (xanax). I was prescribed xanax a couple years ago. They detained me but they weren't able to get a statement and I didn't admit to any wrong doing. The lead investigator "promised"to not file any charges if I agree to a controlled buy. The charges they threatened to use were purchase of oxycodone and possession of alprazolam. Will they file charges or this an empty threat ?