A/N: Sorry this took so long! I got writer's block and life happened. Hopefully the next one will be posted more quickly.
Sherlock drummed his fingers on the cab door, staring absently at the London traffic, seeing but not observing. Talking to Dorset's widow had been disappointingly uneventful – she was clearly innocent, and Sherlock had observed nothing of significance in the house itself – and the meeting had stretched out interminably. He couldn't help but wonder if he should have skipped it entirely in favor of the autopsy. The murdered man's stomach contents were likely to be crucial to the case, and listening to Jenny Dorset dither on about her husband did nothing to stop the corrosive action of hydrochloric acid on Dorset's cake and coffee.
Sherlock shot out of the cab as soon as it pulled up to the curb at Bart's. John paid the cabbie quickly and followed close on Sherlock's heels, both men power-walking to the morgue. They burst in unceremoniously, causing Molly to start with a little yelp.
"Stomach contents. Where are they?" Sherlock's voice was clipped.
Molly stepped away from the corpse, giving Sherlock and John a better view. The body had been cut open in a Y-shape, and the ribs had been open and folded upwards to reveal the chest cavity. A tray next to Molly held the majority of Dorset's organs. Molly gestured to a stainless steel bowl. "It's right there, I was just about to close him up and start on the cranium."
"Good," said Sherlock briskly. "You dissect the brain. John, you take the heart. I'll take a look at the stomach contents. First one done runs blood and tissue tox screens. We'll start with the usual substances, but be sure to keep enough samples just in case." Without further ado, Sherlock grabbed the stainless steel bowl that held Dorset's stomach and swept into the adjacent lab.
John moved over to the tray and found his assigned organ. "Find anything yet?" he asked. Molly shook her head. "Everything looks picture-perfect so far." She picked up a saw from the tray, and John took it as his cue to join Sherlock in the lab. Removing a skullcap was messy business, and he wasn't exactly dressed for an autopsy.
Sherlock had already removed the contents of Dorset's stomach and was taking samples, putting some on slides and sealing others for future testing. Neither man talked as they went about their work, focusing completely on their tasks.
The minutes passed, punctuated only by occasional annoyed huff from Sherlock's side of the lab. Eventually John stepped away from the countertop that held Dorset's heart. "Found something?" queried Sherlock, cocking his head. "I'd give cause of death as a heart attack, probably secondary to a hypertensive crisis," said John. Sherlock frowned a bit, then shook his head. "Alright, start in on the tox screen then."
After a few more minutes, Molly came in with her results. "So far I've found an intercranial hemorrhage over the left parietal lobe." "Hypertensive crisis?" asked John. Molly nodded. "It's strange," she said. "He didn't have any signs of chronic high blood pressure, and he doesn't have any risk factors for such a sudden spike," She frowned a bit, unconsciously mirroring John and Sherlock.
"Well, it looks like we've got a long night of tests to run," said John. "I'm going to run down to the mess to get some food. Anyone wants some crisps?"
...
It was nearly 12 hours later when Lestrade arrived at the lab. John was leaning over a centrifuge, attempting to yawn and drink coffee at the same time. Molly appeared to have fallen asleep with her face resting on the eyepiece of a microscope. Sherlock, of course, looked as if he had just woken after a full night's sleep. Who needed sleep when you had adrenaline?
"So what do you have, Sherlock?" John and Molly jumped a bit at the sudden voice. Sherlock didn't look up from his microscope. "Intercranial hemorrhage and myocardial infarction, both secondary to hypertensive crisis."
Lestrade paused for a moment, processing. "So in English...?" John smiled a bit. He had trouble keeping up with Sherlock, and he was a doctor. He could only imagine how Lestrade felt. "He had a heart attack and a stroke because his blood pressure spiked suddenly," John supplied.
"Oh, okay." Lestrade's face clouded. "Any luck on the tox screen?"
Sherlock kept his face down in his microscope as he answered. "Nothing so far, but I'm confident a more extensive test will provide the necessary information. They'll take some time to run, but between the three of us," Sherlock gestured to John and Molly, "I'm sure we'll be able to get them done in a week or so." John and Molly groaned. Extensive tox screens normally took several weeks to complete; if Sherlock expected them to finish the tests in a week, it was clear they wouldn't be sleeping. "Oh, don't give me that," said Sherlock to the pair. "A man's been murdered; surely catching his killer is more important than whatever trivial things you would otherwise do with your time."
Lestrade shifted where he stood, hands in his pockets, looking uncomfortable. Sherlock's eyes snapped back to the DI, reading the slump of his shoulders, his nervous chewing on his lip. Sherlock's eyes narrowed. "What is it?" It sounded like an accusation.
"Well, the thing is, it's like John said. He had a heart attack, or stroke, or I guess both? Either way, the tox screen didn't turn anything up, and we didn't find any poison at Richardson's. It looks like a natural death, Sherlock, and I believe you when you say it's not, but the Chief wants to close this one as soon as possible– prominent citizen and all that. I'm sorry, Sherlock." Lestrade really did look sorry. He knew there was something off about this case, and while he couldn't put a finger on it, he knew Sherlock could, if he was just given time. But the Chief had refused to budge, and Lestrade's hands were tied.
"What? No!" Sherlock finally looked up. "There's no reason why Dorset would suddenly have a heart attack or stroke, let alone both, and the fact that you found nothing at Richardson's flat means nothing, given the calibre of your forensics team. The obvious answer is that Richardson used a substance that he knew wouldn't show on a standard tox screen. He's a medical man; he knows what wouldn't show up on the tests and he has access to a full pharmacy. He's counting on us giving up now, don't you see?" Sherlock grew more agitated with each word. Richardson had worn his guilt like a shock blanket, and the fact that Dorset had appeared to die of natural causes only fed Sherlock's interest in the case.
Lestrade sighed. "I know, Sherlock. If I could, I'd keep it open. The whole thing feels funny to me. But I can't, Sherlock. I just can't. I'm sorry. The case is closed."