Unspeakable by Sandra Brown.
Two seemingly unrelated events occur when a convicted killer escapes from prison, an unsolved murder case is reopened, and a stranger arrives on an East Texas cattle ranch, but it turns out that this enigmatic man may hold the key to a lot of questions.   Anna Corbett is deaf and mute, but she's not stupid. When the young widow is told by her aging father-in-law, Delray Corbett, that Jack Sawyer has been hired to work their eastern Texas ranch merely as an extra pair of hands, Anna knows that it's really the news of criminal Carl Herbold's recent prison break that has Corbett hiring the tough drifter. Carl Herbold, along with his brother Cecil, swore vengeance against Corbett, their stepfather, for cooperating with the police when the two were convicted of armed robbery.