The most prominent and revered member of Anonymous, Sabu, has reportedly been an FBI informant for months. And thanks to his help, authorities today rounded up the last members of LulzSec, the notorious defunct hacking group he once led.

Fox News reports that the Anonymous leader Sabu is Hector Xavier Monsegur, a 28-year-old father of two living in New York. He was apparently arrested last summer, pleaded guilty to 12 charges in August, and has ben working with the feds ever since.

This is a stunning development for Anonymous. Sabu, using his well-followed Twitter handle @Anonymousabu, had become the most prominent member of the loose-knit hacking collective. Sabu's rise started with the hack of the security firm HBGary in winter of 2010, which leaked chat transcripts show he masterminded. It continued as he led the Anonymous off-shoot LulzSec; off the notoriety gained from LulzSec's summer of hacking mayhem last year he became increasingly respected among Anonymous, acting as the group's de facto spokesman. After LulzSec disbanded over the summer, Sabu was often the first to announce new Anonymous hacks, and he constantly cheerleaded on fellow Anons while spewing out hatred for the U.S. government.

But Sabu didn't fall as his comrades in Anonymous and LulzSec were swept up in raid after raid—in fact he only seemed to grow more bold. This raised some suspicions that he'd turned informant, and those suspicions were right: Today authorities on two different continents rounded up some remaining key members of LulzSec "acting largely on evidence gathered by" Sabu, according to Fox News.

Who knows how many other Anons Sabu has snitched on. Just last week, he urged hackers to come forward with "data to publish (big dumps, source codes, cache of documents, etc)." Sabu was a linchpin of Anonymous, and there are going to be a lot of worried hackers out there today.

Update: Anonymous Snitch Tried, and Failed, to Pass Himself Off As an FBI Agent Last Month