If a detective "has" been investigating a known residence for drug transactions should there be paperwork or evidence to prove that if requested?

I have been arrested over a year and a half ago by the same detectives 2 times for marijuana possession and this other night i was caught again.. The report said he had been investigating the residence i was at for known drug transactions. my car was parked across the street and i was at my friends house for 4 hours as a goodbye before he went back to school. The cops do know my vehicle as they have impounded it twice before in the past. I believe i was targeted and followed because of who i am with know evidence as to what i had in my vehicle. I did not smoke nor have marijuana on my person at any point while i was there. If this detective was truly investigating this property and surveilling it, which is not true, wouldn't there be some sort of paper work showing an open investigation? This is but one of many holes in the officers police report, but it is the very first sentence of the report i would like an opinion before i ask my attorney which i have already.