I was watching the episode 'Better Call Saul' in Breaking Bad. It has the scene where Brandon Mayhew is sitting in the interrogation room of the APD and Saul Goodman comes in and the scene goes on. After talking with Badger, Saul goes near a water fountain and he sees an APD officer walking with Hank Schrader.
Yes, Saul knew that DEA are involved in Badger's case. But how did he exactly knew that Hank was the DEA agent looking out for Badger. It could have been possible that the APD officer was also working on another case and the bald fat guy walking in civilian clothes might be some other officer from APD.
Saul Goodman walks up to Hank as if they know each other. The only thing that is sure is that Hank knows Saul from the advertisements, but knows nothing personally.
My best assumptions would be that,
Saul hired his PI to investigate who in DEA will be handling the case. Bingo, Mike knows in and out of APD, couple of calls and Saul has his answers.
Since the blue meth case is high profile, APD will only be focusing on it as well as DEA will be handling it. Thus, the person with APD is obviously/must be DEA agent. Saul deduced this.
I haven't seen 'Better Call Saul' series. So maybe, Saul has encountered Hank previously, but Hank doesn't remember him.
Does anybody have better answers?