The Sidewalk Hilton — Bruce Cook

Hired to find a visiting Chicago millionaire missing in Los Angeles, private investigator Chico Cervantes embarks on a real Phoenix of a case; each time the Latino detective thinks he's finished it off, it rises again to confound him.
It isn't long before he finds Benjamin Sterling's murdered body in the tycoon's room in a posh hotel. But the man's face wounds make identification difficult, and Sterling's daughter insists - and proves - that it is not her father, although it was obviously intended to be taken as him.
Benjamin Sterling soon turns up alive and well. He's been living in a city park with a congregation of homeless men. The millionaire wants to fund a project to relieve homelessness; to get it off the ground, he wanted first-hand experience of the lifestyle.
Although no one knows who killed the stand-in, who turns out to be one of the city's homeless, Sterling plucks an associate from among the men. Julio Alviero is a genial Mexican-American small-time con man whom Sterling takes back to Chicago with him as a "consultant." For who is more able to advise on what will work and what won't than someone straight from the streets? Except that when the real Benjamin Sterling is found dead, his "consultant" is arrested and Chico is once again on the move, this time to Chicago to extricate his friend from the toils of the law and uncover a very persistent killer.