"I know that the public, after the magistrate had discharged Arthur Greenhill, were quite satisfied to think that the mystery in Percy Street was a case of accident--or suicide." "No," replied Polly, "there could be no question of suicide, for two very distinct reasons." He looked at her with some degree of astonishment.

She supposed that he was amazed at her venturing to form an opinion of her own.
"And may I ask what, in your opinion, these reasons are ?" he asked very sarcastically.
"To begin with, the question of money," she said--"has any more of it been traced so far ?" "Not another L5 note," he said with a chuckle; "they were all cashed in Paris during the Exhibition, and you have no conception how easy a thing that is to do, at any of the hotels or smaller _agents de change_." "That nephew was a clever blackguard," she commented.
"You believe, then, in the existence of that nephew ?" "Why should I doubt it?
Some one must have existed who was sufficiently familiar with the house to go about in it in the middle of the day without attracting any one's attention." "In the middle of the day ?" he said with a chuckle.
"Any time after 8.30 in the morning." "So you, too, believe in the 'caretaker, wrapped up in a shawl,' cleaning her front steps ?" he queried.
"But--" "It never struck you, in spite of the training your intercourse with me must have given you, that the person who carefully did all the work in the Rubens Studios, laid the fires and carried up the coals, merely did it in order to gain time; in order that the bitter frost might really and effectually do its work, and Mrs.Owen be not missed until she was truly dead." "But--" suggested Polly again.
"It never struck you that one of the greatest secrets of successful crime is to lead the police astray with regard to the time when the crime was committed.

That was, if you remember, the great point in the Regent's Park murder.
"In this case the 'nephew,' since we admit his existence, would--even if he were ever found, which is doubtful--be able to prove as good an _alibi_ as young Greenhill." "But I don't understand--" "How the murder was committed ?" he said eagerly.

"Surely you can see it all for yourself, since you admit the 'nephew'-- a scamp, perhaps--who sponges on the good-natured woman.

He terrorises and threatens her, so much so that she fancies her money is no longer safe even in the Birkbeck Bank.