Hot Blood by Ken Englade

HELEN BRANCH LEFT BEHIND A HUGE FORTUNE--AND A MYSTERY THAT WOULD HAUNT THE NATION FOR YEARS TO COME.
A coal-miner's daughter, she was a beautiful hat-check girl who snagged a millionaire . . . only to become an eccentric, pet-loving widow who, one day, disappeared without a trace.

WAS SHE A VICTIM OF "THE GALLOPING GIGOLO?"
Richard Bailey was an admitted swindler who spent years persuading rich women to invest in bum horses.even though he claims not to have harmed Helen Branch. Other suspects included a champion rider and an Olympic hopeful--each with dangerous connections to wealthy horsemen, and both with cold-blooded schemes to achieve their mission.

ONE MAN IS DEAD-SET ON FINDING OUT.
When Assistant U.S. Attorney Steve Miller launched an investigation into Helen Branch's death, he went from the polo grounds of Palm Beach to the lavish horse farms of Connecticut to Kentucky's thoroughbred stables in search of answers. What he learned would cast a dark shadow on one of America's favorite pastimes. . . .