Yes. The Service Department at headquarters sometimes sends in two specially trained Elders to clean up messes and police problem congregations. I think that's what you heard about. They aren't called secret police but have some kind of innocent sounding name like Special Needs Elders. Also, sometimes Governing Body members will have a long-time, trusted friend such as one of the Special Pioneers, male or female, go into a congregation and keep an eye on the Elders themselves. There's a lot of covert spying by Bodies Of Elders especially these days.
It's no surprise a lot of former elders who left a long time ago don't know about these things because the number of pedophiles and those of similar ilk were not as numerous in years past. But since 1972 they have become more numerous because the Service Department doesn't want to lose any more Elders than necessary. If an Elder molests a child and confesses, then if he has done so after two or three years have passed and to the other Elders it appears he still has Jehovah's (or their own) blessing, then they say he is forgiven and he is kept as an Elder.
The farther you go along in time, the worse the crisis. District and Circuit Overseers do their best to shut people up. They sometimes target what they call trouble-makers or "apostates." I think the African-American brother Greg Peters (or Peterson, Petersen or a similar name) in Texas was finally knocked out of the organization by such a person. I also think the DO or CO who did it had some kind of Slavic name, not Yarozowski but something of that order. I'm getting old so a bit forgetful, but these things are all facts, and you may be able to confirm a lot of it if you google around a lot.
Over the years the Society has appointed special teams of Elders to go in and try to weed out apostates or disreputable Elders, reorganize and police the flocks at Bonham in Texas, Richmond (Michigan or Missouri), southern California and inside New York City. I signed in just to answer your question. Most posters will tell you it's a lie or joke but that's why they are "secret" police among JWs. Don't fool yourself. Local BOE's also do their own policing, spying and harrassing when it's to save their own bottoms.