Ann Cohen is a character in DEXTER.
She was a single woman who was raped and killed by her car dealer whose name is Roger Hicks. She went to Roger in hopes of buying a new car. When Roger met her he ran a background check on her and found everything he needed to in preparation to kill her. Roger went to her house, talked his way inside and then raped and killed her. Dexter later discovered this while investigating a similar killing one month after Ann's death and found out Roger killed her.