link that worked. now it could help crack dozens of other cold cases. thelma gutierrez gives us an exclusive look inside the lab that cracked this case. reporter: behind these doors at the department of justice crime lab in california, forensic investigators solved a landmark cold case that could change the way police investigations are conducted. we went inside for an exclusive look at the new dna technology that led detectives to an elusive killer dubbed the grim sleeper. it was the 1980s, a serial killer was terrorizing south los angeles. most of his victims were young african-american women, some had been shot with the same.25 caliber firearm. some had been strangled. some sexually assaulted. their bodies dumped in ael liz. over the years, los angeles police would follow numerous leads that went nowhere. in 1988, after eight murders and an attack on the potential ninth victim who got away, the killing