Most news organizations don't show under cover police officers on television, I know where I live as well as other places I've lived in the past, it's against the law to photograph police officers.
Bust a dope dealer today, and there will be another dope dealer working that same area the next day.
When I was younger they did and I assume still have these programs, the officers don't get made, for one they don't make the bust, this is a television show, so some police procedures aren't actually what happen in the real world.
They don't have to fly people anywhere, the last time I checked the regular police officers go undercover in the same neighborhoods all the time, students talking to each other would also have to apply to the criminals that regular undercover officer arrest as well.
Most drug dealers have a territory they work, and a lot of times get their drugs from the same supplier, yet the undercover officers rarely get their covers blown.
What adult criminals don't talk?, they arrest the undercover along with the suspects.
The creators got the idea for this show from programs that already existed, there are enough of these cases, they also use officers to buy cigarettes and alcohol, they use police academy cadets.
In certain cases they don't always release the name of a cop even if a cop gets shot by friendly fire, if they put their real name in the paper who would know, undercover cops use aliases all the time and as I said previously they never show their pictures, unless they die in the line of duty. I've never seen a televised trial where the undercover officers were shown on camera.
Non-undercover detectives are seen on television or in newspapers, how many people will remember what they look like.
Most people who witness a crime, can't give a good description of the criminal.
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