DETECTIVES IN Austin, Texas are trying to a link a troubling 1988 cold case to the chillingly similar slaying two years earlier of Christine Morton, pictured right. Now, the working theory is that a serial killer may have been at work although Morton's husband has been in prison for nearly 25 years for the crime. According to the Austin American-Statesman, Debra Jane Baker of Austin was beaten to death with a blunt object in her bed while she slept--identical to Morton's slaying 12 miles away. Morton's husband has been trying to get DNA testing to determine if 