Task: Question Answering
Input (English): Passage: A mysterious artist - and psychopath - named Ronnie Mason, steals a dead woman's wedding ring and money and leaves a fake suicide note. The woman's husband, Thomas Turner, when questioned by the local police, believes his dead wife might have been seeing Mason behind his back. He also believes his wife was murdered, but in the absence of other evidence, the police list it as a suicide and drop the case.
Mason leaves town, changes his name to Marsh and, using a limp he acquired jumping from the dead woman's bedroom window and a veteran's pin he steals from a fellow passenger on the L.A. bus, passes himself off as a wounded soldier and rents a room in the house of public stenographer Hilda Fenchurch and her younger sister Anne. To the consternation of professor Andrew Lang, who secretly loves Hilda, she falls for Marsh.
The scheming Marsh learns that Anne might inherit a great deal of money, so he suddenly switches his affections toward her. Hilda is jealous and suspicious. She plots to lure Marsh to a beach house and poison him. She is unable to go through with it, but when Marsh runs off, he is surprised by Thomas Turner and plunges off a steep cliff to his death. 
Question: What is Ronnie's assumed last name?
Output (English): Marsh.