Meanwhile Dignum had been given reason to become concerned about Billy. Questions had been raised about the SIU's operations against Costello so the undercover files had finally been reopened. Was there an undercover in place against Costello or not? Dignum knew about Billy as an undercover, but not about Billy as an active cop because the files had not be kept synchronised. Dignum had to tell Ellerby that their Costello undercover had not reported in for a month and might have been "removed" when Queenan was killed. Dignum attempted to open Billy's personal file, but was locked out as Billy had altered the password. That really gave Dignum a headache.
Then Ellerby started getting anonymous information on Costello's operations, and looked to Dignum for answers. Answers that Dignum didn't have. Dignum checked out Billy's house, but only learned that Billy had not been seen for at least a month. The local cops told Dignum that Billy had asked them to mind the house, but as they didn't know that Billy was now a cop Dignum was left baffled and wondering if Billy had jumped ship and was in hiding or had been sent away by Costello. Or was Ellerby's mysterious contact Billy? Of cause Sullivan knew that Billy was on active duty and enjoyed Dignam's discomfiture, never hesitating to rub salt in whenever Ellerby gouged Dignam.
Dignum only learned the truth at a monthly staff meeting where staff performance was being discussed. Dignum had to hide his shock when he heard about a certain recent recruit called Costigan who was not pulling his weight, slacking during the day and avoiding night duty. Dignum checked in the rosters and soon found Billy. Dignum was enraged. However on reflection, Dignum knew perfectly well that Billy should be performing a lot better than this. What was that worthless punk up to!
Dignum asked around Billy's section but Billy was never in and Dignum did not wan to cause a fuss, yet. Dignum had to wait until that section's weekly group meeting was over, and then pounced.
Grabbing Billy, Dignum frog marched him into a quiet alcove where Dignum demanded answers in his most physically and verbally violent, and insulting, manner. Billy had expected this moment and retaliated by telling Dignum that he knew who Costello's moles were, but getting evidence that would stick was another matter. Billy then bluntly pointed out that he had achieved more in one month than the SIU had done in six months. Billy then said that this was hardly the place for a private conversation. Dignam told Billy to meet him downstairs in the records basement.