How did the Blackmailer get the other Glove?

Had he not visited the artists flat after the killing and found it there. Remember the artist had already picked up his mail which included a note from the blackmailer ,so he already had something on the artist and intended to collect on it.

In her haste to leave Crewe's apartment, Alice forgot both her gloves there.
Right after she sneeks out to the street, we can see Tracy's Nosferatu-like shadow growing on the building front. Clearly, it means that Tracy paid a visit to the apartment after the killing: it was then that he got one of Alice's gloves.
As you know, the other glove would be found by Frank the next morning while searching the apartment for clues. He acnowledged it was hers because of its holes: the holes he made fun about at the restaurant the night before.

João Pedro

Actually, the balckmailer himself explains how he got it. The shadow approaching the door of the apartment house implies that someone is going to go to the apartment immediately after the murder, and when he produces the glove, he says he looked everywhere for the other glove, but that Scotland Yard types are much better at that sort of thing.

I thought the exact same thing bc it also made a point to show her with only one glove on when she was walking home!! It clearly is emphasized she is missing a glove bc she has both hands to her chest when she sees the crossing guards white gloved hand out she has a vision of the rapists hand hanging off the bed, then flashes back to her looking frightened with one gloved hand and one missing a glove! So how did the blackmailer AND the boyfriend find a glove when she was also wearing ONE home!!?! This must be a goof bc it was definitely made a point to show her hand missing a glove on her walk home.