An ex-convict accused of preying on prostitutes was convicted of murdering four women and attacking three others in the Fresno area over a two-year period. All but one of the victims were black prostitutes picked up in an area noted for streetwalkers. The murder victims had been raped and left without identification and were found at least partially nude in rural Fresno. A jury deliberated eight days before convicting Wilbur Jennings, 45, who is black, of 19 counts involving seven women. The jury acquitted the Selma auto mechanic of rape and oral copulation in another case and deadlocked on sex charges involving two other women. Fresno County Superior Court Judge Mario Olmos ordered the jury to return Monday to decide whether Jennings should spend life in prison or die in the gas chamber.