Cops hardly ever have informants wear wires, it's all based on testimony, and during a controlled buy situation there's a very fine line the informant has to walk. Here's a typical scenario, Snitch get's caught with some herb, or coke, or heroin, or meth or... You get the picture, typically he's just hauled to jail, and waits for arraignment unless 3 things happen to take place, 1, a member of vice squad, happens to be at the station, and he got caught with enough of the drugs to make it a bigger deal, 2 He's really unlucky, and gets snagged by vice in the first place, or 3 he has a pre-existing relationship with a detective, and he calls on a favor, so he can work off the charges before being put in the system.
So now we have a basic idea of how he started working for them, and why, but now we want to know what kind of work he's doing. This is how it works, The police will take the individual to different houses, that they think are drug locations, they drop him (or her) off with the information about the person inside, and it's the informants job to get that person to sell to them. They give the informant X amount of money that's marked, and before the controlled buy begins, they give him a pat down, to make sure that he's getting the drugs from a particular person, and not bringing the drugs to set someone up.
The informant isn't allowed to drink, or do any drugs during the buy, or the police aren't allowed to use that information in court. After the buy happens, the vice squad, (who have been monitoring the situation from cars (they drive in packs of 2-
will pick the buyer up, take the drugs, and the informant is done for the day. They also do one last pat down before they cut them loose, but the whole process is pretty relaxed.
Most informants will use the controlled buy as a way to get drugs themselves. They'll pocket half of whatever they bought, and give the police the rest, (that's one of the reasons the police have a hard time keeping track of actual cost of drugs, you always here on the news some story about them finding 5,000 dollar ounces of pot, and 5 million dollar kilo's of coke, this is one of the reasons their numbers are so high.
Here's the thing, your fine, the police don't want to blow their cover by arresting you for the pill you never sold him, more than likely they'll think the informant did the drugs himself, and is lying about you taking his money. That said, I think your a right twat for stealing that kids fix money. Junkies aren't bad people, they're desperate people, they want to feel the same way you do everyday, only they have to spend 50 a day to do that. Most likely you just stole that kids ability to get a good nights sleep, and to not have to do something desperate for his fix. You can't say what you want, but I think you just have a guilty concious, because you put that kid in a lot of pain, my reply is written merely as a way for others to get a feel of how LEO works. Have a good time being a dickhead.