author charles campizi, former chief of the nypd internal affairs bureau talks about his book with former nypd officer and author of "once a cop." >> i spent 41 years in the nypd. i saw acts of courage, bravery, integrity. but there is always that small number of cops who keep up at night. when i was a commander, everyone knew the person or maybe who two that you didn't trust and the other officers didn't trust him or her either. so what i did when i went to internal affairs a brought the commanding officers onboard. and we would meet with them on a regular basis. and i would ask them questions like, who in your command are you a little concerned about? who in your command keeps you up at night? >> watch "after words" sunday night at 9:00 p.m. eastern on c-span2's book tv. >> irs commissioner john koskinen delivered the keynote address at a luncheon hosted by the national press club in washington, d.c., just a couple weeks before the annual tax deadline. commissioner koskinen focused on meeting taxpayer's needs and cybersecurity threats. after his remarks, commissioner koskinen took quest