MCKEESPORT (WPXI) – An arrest has been made in the murder of 26-year-old Karli Short. Short, of McKeesport, died in September. Short was five months pregnant when she was murdered. Through their investigation, detectives determined that the father of the unborn child, 25-year-old Isaac Smith of McKeesport, was responsible for the killing. With the assistance of the Allegheny County District Attorney’s Office, detectives obtained an arrest warrant for Smith charging him with criminal homicide and homicide of an unborn child. Smith was arrested by Allegheny County Homicide Detectives and Pleasant Hills Police at approximately 7:00 pm on Friday. Smith will be housed at the Allegheny County Jail to await arraignment.