"Not necessarily," replied Roper, dryly; "but this, that if Vassalla knew she was on board that night, he also knew she committed the murder, and would therefore have a power over her; but her determination to stop the marriage shows that she must have some power over him; so that either she is innocent, or he committed the murder himself, and she can force him by fear of exposure to do what she wants."
"And which of these theories do you think is right?" asked Foster.
"I am doubtful," said the detective, becoming a little agitated; "but I--I have a third theory."
"Yes?" said Ronald, in a quiet tone, looking strangely at the detective.
Roper arose to his feet, and took a walk up and down the room for a minute, then turned to the young men, who were puzzled by his curious manner.
"Of course, it's only a theory," said Roper, nervously; "but--but--I can only tell you what I think."
"Tell us, in heaven's name!" cried Foster, rising.
"Then I think Miss Carmela Cotoner committed the crime."
"What?" Ronald sprang to his feet, and made a spring at the detective, but Foster caught him and held him back.
"Be quiet Ronald, be quiet," he said, firmly.