Dark Angel by Sidney Sheldon

This was his first major murder, and one of the most violent and bloody crimes faced by LAPD detective Danny McGuire. Andrew Jex, an elderly millionaire art dealer, was brutally murdered in his Hollywood home, his lifeless body tied to his naked young wife. The beautiful Angela Jex had been raped and beaten, barely surviving the attack. As Danny stared into her deep, haunting eyes, he swore he would find the psychopath behind this brutal act. But the investigation yielded no conclusive evidence, and within days of Angela's release from the hospital, the beautiful young widow—Danny's only witness—disappeared. For ten years, Danny McGuire could not forget Angela Jex's beautiful face and the horrific crime that shattered her life; his obsession nearly drove him mad. Now in France, thousands of miles from the past—with a new life, a new job with Interpol, and a stunning new wife—he's happier than ever... until he meets Andrew Jex's estranged son, Matt Daly. Fueled by his curiosity about his father's murder, Matt has been digging into the cold case—and making some shocking discoveries. Three murders almost identical to his father's have taken place around the world. The victims were elderly, newlywed millionaires, and their young wives were assaulted. In each case, the widow, the sole beneficiary of the will, donated her newfound fortune to children's charities and then disappeared. Could this be true? Has Jex's killer struck again? If so, Danny knows he must tread carefully or risk losing everything forever. The evidence points to a single killer—a brilliant and ruthless criminal who travels the world under a series of assumed identities, cleverly staying one step ahead of the law. Teaming up, Danny and Matt pursue this intriguing shadow from Los Angeles to London, from New York to Italy and the French Riviera, in a thrilling chase filled with promising leads and frustrating dead ends. When another murder that fits this description occurs, Matt heads to Hong Kong, hoping to get answers from the latest widow, Lisa Baring, and perhaps uncover the damning evidence they need. But Matt is captivated by her striking beauty, nearly sabotaging the investigation, and Danny wonders if Lisa is truly a victim or something more sinister. When a breakthrough in the case sends Danny to Mumbai, he realizes he has to move fast, because the clever killer is about to strike again. A fast-paced story filled with mystery, magic, intrigue, and stunning twists leading to a stunning conclusion, Sidney Sheldon's "Dark Angel" captures the essence of Sheldon from page one to the last.