On June 28th…

(Source: A Day by Day Chronology of Mr. Sherlock Holmes According to Zeisler and Christ, compiled by William S Dorn)

Illustration by Sidney Paget for The Strand Magazine (1891)

June 28, 1890: John Turner confessed to the murder of Charles McCarthy. [BOSC]

“Well, it is not for me to judge you,” said Holmes, as the old man signed the statement which had been drawn out. “I pray that we may never be exposed to such a temptation.”
“I pray not, sir. And what do you intend to do?”
“In view of your health, nothing. You are yourself aware that you will soon have to answer for your deed at a higher court than the Assizes. I will keep your confession, and, if McCarthy is condemned, I shall be forced to use it. If not, it shall never be seen by mortal eye; and your secret, whether you be alive or dead, shall be safe with us.”

Chips says: To me, this story was written to have the reader have sympathy for the murderer already under the sentence of death. It worked.