Sherlock Imagines

Sherlock: Why are you looking at me like that? (part 3)

Imagine that despite your better judgement, you have agreed to accept Sherlock's help to solve the murder of Mycroft's assistant. The victim is also the wife of the Prime Minister's chief advisor so Scotland Yard is very interested in making sure the case is thoroughly investigated.
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Sherlock peers into the microscope with a smile, "There you are, you little buggers."

You laugh at his description of the tiny diatoms, microscopic algae that only live in freshwater. Incredibly, these little organisms are your clue to the location and time of death of your latest victim.

Sherlock lifts his head, and you can see the many wheels spinning in his mind. "So, (Y/N), you say the diatoms have traveled throughout the victim's lungs and circulatory system."

You nod and pick up one of the slides and place it under a different microscope. "Correct. If you look here, you'll see the sample bone marrow from the victim's body."

You turn the focus dial of the microscope and peer down. As you look up, Sherlock is standing close beside your arm, waiting impatiently for his chance to see. You step out of the way and Sherlock peers into the microscope.

"There are 8,000 known types of diatoms," you explain to him, "and if we can find at least five complete varieties in two or more of the victim's internal organs, we have a winner, Mr. Holmes," you grin with satisfaction. "I've already found diatom matches in the victim's lungs, spleen and bone marrow."

Sherlock moves from one microscope to the other. "This diatom sample looks different from the others. Why's that?"

"The sample you're looking at was taken from a freshwater source." You sigh as you take your glasses off and rub your eyes. "I have another 32 slides to analyze. I have to match the diatom colonies from one of those location samples with the ones in the victim's body." You smile at the rush you always get when you find a match. "When I do– bingo. I've found the scene of the murder!"

Sherlock's eyes gleam with anticipation. "Now, (Y/N), you're speaking my language. What are we waiting for?" He takes off his coat and rolls up his sleeves, raising an eyebrow at you. "So you believe the strangulation marks on the victim's neck were not the cause of her death."

You grin as you wonder why you hesitated in allowing him to help. "Correct."

"And why is that?" Sherlock's mouth twitches and you realize that he already knows the answer.

"Because even though the marks on her neck give evidence that the perpetrator did mean to do her harm by attempting to strangle her, the high levels of diatoms in her body indicate that she actually died by drowning. In my experience, attempted strangulation is often done in acts of domestic abuse, which may mean the killer knew the victim well."

"I'm impressed, (Y/N). Certainly, I underestimated your skills of deduction." The corners of his mouth turn up. "I agree with your findings. I also examined the body and found the strangulation marks on the victim's throat did indeed damage her larynx but would only have rendered her unconscious. She was drowned, while she was still unconscious."

You look at Sherlock and realize you had completely misjudged him. His father was right. Sherlock was just like his mother.

"Also Molly, ah, Doctor Hooper, scraped some skin fragments from under the victim's fingernails. She's analyzing the DNA, but I'm sure if we examine our suspects, we'll find our killer. He'll surely have nasty scratch marks. My guess would be on his lower arms as the victim would be desperately trying to pull his hands off her throat."