What methods do Police use to infiltrate Mafia? Do they mainly get associates and made guys to become rats on higher-ups?

The best description of how they do it is in the Donnie Brasco book, but they can only do that once in a while after the first time. Now mobsters are more suspect of anyone new.

9 times out of 10 these days it is from the inside out, not the outside in.
They find a weak link rat and threten him with RICO and a life sentance, and they flip and become FBI informents.
Pestone was one in a million.

The Mafia has gotten much more cautious about making guys because of the Law Enforcement infiltrations of the past.
Guys like Joe Pistone (Brasco) ,Jack Garcia (Falcone),and Ed Robb(Supposed owner of the King's Court in Fla) really made them overly paranoid.
According to Pistone,after his operation ended,the Mob re-instated the old rule about guys making their bones to become made men.
Also,the prospective member must be vouched for by two guys,not one.The sponsors must have known the candidate at least 15-20 years.
With the constant technology advances and better intelligence,the Feds are able to do quite a number on the Families from the outside. I agree with the other posters that the only real avenue for getting inside info is to jam a guy up on a major charge and try to flip him. Bear in mind that in the Rico era,it is much easier for a guy to be facing 50 to life for relatively minor stuff than it was years ago.

I just mentioned on another thread about the govt using informants. I know many of you guys are "fed-up" hearing about The Outfit, but it seems that as far back as the the 30's and 40's there was a lot of talk about informants in the FBI files. I'm talking about people in the upper echelon of The Outfit who were never exposed, not undercover agents.

Don't know much about other organizations, but apparently Chicago had a rather sizable pool of informants.

Would like to hear your thoughts.

The Arm is right. They grab someone, charge them with heavy time, flip em, give them a neat Dick Tracy recorder watch and a pair of cam-corder sunglasses and send the chump on his way to WITSEC via 3-4 years of puppetry at the behest of government job ladder climbing jerkoff. It's pretty easy work, good for fluffy hands and weak non-creative types.

A veteran FBI agent told me that most of their cases are solved because of a "Squealer" who might just be a jealous "Friend"

batteries and wires is all the police need for any criminal organization in the U.S.