Who is Tap Granger from 'F' Is for Fugitive: A Kinsey Millhone Mystery and what is their importance?

Tap Granger and Bailey participated in several robberies together, and Bailey ended up going to jail for one of them. Tap straightened out after Bailey went to jail for killing Jean. He is married with four children and one on the way. After Bailey is arrested again, Tap gets a phone call telling him he has to help Bailey escape. Tap shows up at the courthouse with a gun filled with rock salt and gets Bailey out. Tap, however, is killed as he attempts to leave the courthouse.