On May 10, 1964, Dexter saved both
Frank Sinatra's life and the life of Ruth Koch (wife of Producer
Howard W. Koch), during production of the World War II film,
L'île des braves (1965), in Kauai, Hawaii. Sinatra and Koch were swimming at a beach when they were swept out to sea by the outgoing tide and nearly drowned in high billowing waves. Co-star Dexter swam out and rescued them together but were not able to return to shore for nearly 45 minutes. In the waves, Sinatra reportedly became separated and murmured "Its all over...please take care of my kids...I'm going to die." Towards the end, both Sinatra and Koch had fallen unconscious for several minutes before two surfers arrived to help Dexter take them to shore. Dexter was later awarded a Red Cross medal for his bravery. When Dexter, who was just two years younger than Sinatra, later advised Sinatra (born 1915) not to marry the then-20 year old
Mia Farrow (born 1945), who was 30 years Sinatra's junior, Sinatra ended their relationship.
