“Don’t be absurd! It’s obvious she did it. Why would she have confessed to a crime she didn’t do?” protested the Inspector. “I’m sorry Mr. Holmes, but this time you’ve got it wrong; she’s a charming girl, but that didn’t stop her murdering her blackmailer.”
“My dear Inspector, did you ask her how she killed him? Did she tell you where she got the knife?” Holmes replied calmly.
“Now, there’s a funny thing. She never mentioned the knife. Perhaps she forgot”

“But he was with Dr Harrap and no-one saw him leave the surgery.”
“I think you’ll find there’s a back door to the surgery which leads straight out into the street. Fifteen minutes is long enough to rush into a house get a knife and…” But as Holmes was about to finish his sentence, the door burst open and there stood Lonsdale, his service revolver in his hand.

“Well done, Holmes. I thought you might come to that conclusion and so I took this little precaution.” Lonsdale’s face was contorted with anger as he spat out these words: “It was a pleasure to destroy that animal. Now I’m afraid I have to do the same to you.”
The Inspector looked on in amazement as Sherlock Holmes, with immense agility, threw himself at his assailant and quickly disarmed him. “You can’t prove anything,” Lonsdale shouted as he was led away.
Holmes brushed himself down and, with a look of utter contempt, made his final comment: “I’ve always disapproved of your politics, Lonsdale, but I never thought you capable of anything as low as this.”