>> the dna matched back to both, a commingling of matthew's blood and natalie's blood. and there is all this forensic evidence that starts to tell the truth as to what happened that night. >> in the mirabals' apartment, investigators found evidence of motive. matthew had purchased a $250,000 life insurance policy on natalie that was due to expire three days after her murder. the insurance company revealed that matthew originally tried to buy a million-dollar policy. >> he made $19,000 a year. so the insurance company said, you know, we don't think we're going to give you a million dollars. would you settle for $250,000? and he jumped at it. he said, yeah, i'll take $250,000. >> matthew mirabal was arrested and charged with first-degree murder. >> matthew is just pure absolute evil. the way he lived his life, what