Sherlock S01E01 Sherlock pretends to be the deceased and sends a text message to the murderer. So what?

Shylock pretended that the deceased sent a message. From the killer's point of view, the person he just tried to kill is not dead. After eating the poison, she fell into a coma, but now she wakes up, and may forget what happened before and ask him to meet, so the murderer panicked and rushed to the place where Shylock asked him to go.