Mortal Sin — Julia Derek

When wealthy lawyer Martha Moran is found strangled to death in Central Park, Detectives Cooper and White believe the murder was premeditated as well as personal. They have three prime suspects --- her unfaithful husband, her best friend who's secretly a dominatrix, and her jealous, mentally unstable kid sister. All three have strong motives to want to see Martha dead, and all three have weak alibis for the night in question. Did one of them kill Martha or is the truth more complicated than it appears on the surface? NOTE: MORTAL SIN is the fifth murder mystery in the COOPER AND WHITE Series. All books are stand-alones and can be read in any order. They contain no sex and little violence.