Greenwald has been writing about this for a while.

http://www.salon.com/2012/02/22/nypd_spying_program_aimed_at...

http://www.salon.com/2012/02/28/the_nypd_spying_controversy_...

http://www.salon.com/2010/11/28/fbi_8/

http://www.salon.com/2011/09/29/fbi_terror/