On August 22, 1955, St. John spoke on the phone for the last time with Robert, who described him as "very despondent". St. John died either that night or early the following morning. The by-then divorced St. John was found at the 170 East 79th Street Manhattan penthouse apartment of Frances Stratford, with whom he had been involved since at least September 1954, when they took a vacation together to the Bahamas. The day before his death he had also called his son Michael, who was at work in the St. John Publishing office to tell him that he was being blackmailed. But he would not reveal his whereabouts. The police, pending an autopsy, listed the cause as an apparent overdose of sleeping pills, and gave his age as 54. He had been residing at the New York Athletic Club at the time of his death. St. John's son Michael compared his father's death with that of Dorothy Kilgallen and said that in addition to alcohol, his father was addicted to amphetamines.