What role does Simon Rome play in Milo's investigation in the book, The Wrong Case: A Novel?

When Milo takes on the Raymond Duffy case, Simon gives Milo information on Raymond's known associates and even locates one of these men before Milo. Simon begs Milo to be made a part of the case. Finally Milo relents and gives Simon a simple assignment. A few hours later, Simon is found dead. Milo knows that Simon was sober and that the death was not accidental and he vows to find Simon's killer. Simon was like a father to Milo.