Their first stop was back at the ballroom. The eyes of the kitchen and waitstaff were on them both, but Dupon ignored them and trotted toward a table near the back of the room.

“Minister, given your perfect memory, can you please confirm if this is the table where Mr. Vanderbull and West Walnut were seated? I believe it was one, correct?” Dupon asked.

Turing nodded. “You are correct,” she said.

“And do you remember who sat where?”

Turing nodded once again. “This spot,” she gestured, pointing out the seat, “belonged to Mr. Vanderbull. This one, directly to his right, was occupied by West Walnut.”

Dupon looked at the table. “Hmm… do you happen to notice something missing from this table?”

“I do. It seems this table was cleared. All plates have been removed.”

“Oi!” Neighstrad growled, whirling on the waitstaff. “Didn’t we tell everyone to leave things just as they were?! We’ve got an investigation going on here!”

“But Chief Inspector,” one of the waiters said, “we did as you asked! We didn’t touch any of the plates!”

“I believe he is telling the truth, sir,” Dupon said. He swept a foreleg around the ballroom. “Look at all the other tables. All the food that was served is still sitting where it was when the dining service was suspended.”

Neighstrad blinked and looked around. “So it is. Wait, then who cleared the table?”

“An excellent question,” Dupon said. “Well, did anypony happen to see?”

No one spoke up.

Dupon turned to Turing Test. “Your thoughts, Turing?”

She tapped her chin a moment, considering the possibilities. “I conjecture that somepony must have cleared the table and disposed of the food during the confusion caused by the discovery of Beacon Bomber’s cadaver.”

“My thoughts exactly,” he said.

He looked around and spotted a garbage bin located near the cluttered hors d'oeuvres table. He trotted over to it and made a face. “Hmm, I don’t relish digging through this rubbish, but it seems we must.” He spotted one of the officers nearby and beckoned him over. “Constable, could you give us a hoof and—”

“There is no need,” Turing said. “Engaging U-Mode.”

There was a mechanical whirr as a panel opened on her forehead and a metallic horn spiraled out. A moment later, it began to glow with magical energy and the contents of the bin were levitated out as Turing separated out the components into clusters that somewhat resembled the meals that they’d once been part of.

“Waldorf salad remnants identified; now isolating,” Turing said, pulling them out and piling them back on the plate. “My apologies, but that is what you were looking for, correct?”

“Indeed,” he said, smiling. “Quite a handy trick there, Turing Test! Now, assuming that this is what made West Walnut so sick, I’d like to test this. Do you know if any of the symposium guests have the necessary equipment?”

“In fact, I am the necessary equipment,” Turing said. She peered closely at the Waldorf salad on the plate and her eyes began to glow brightly. “Scanning… scanning…” There was a ding, and she said, “Spectrographic analysis complete.”

“Another good trick!” Dupon exclaimed. “Though is the chime really necessary?”

“Ponies seem to expect it.”

“Hm. And what can you tell us about it?”

“The chime?”

“No, the salad,” he huffed.

“Understood. It contains celery, grapes, apples, walnuts, and mayonnaise.”

Dupon frowned.

“...And a small amount of an unknown organic substance in the latex family.” Turing raised her head. “It is toxic.”

He smirked. “As I suspected.”

“Do you believe that—”

“Before I say more,” he said, holding up a hoof, “I’d like to remove all doubt. Come, Turing, let’s go.”

“Please clarify: go where?”

“To the bathroom.”

Turing tilted her head. “You are welcome to go by yourself, but as I lack an excretory system, that will not be necessary for me.”

Dupon rolled his eyes and beckoned for her to follow.

They soon arrived at the entrance to the stallion’s restroom. Dupon went inside.

Then, a moment later, he poked his head back out. “Er… Minister? Aren’t you coming?”

“Ah… while I realize that I am a robot, I am still female, and it is against social protocol for a lady to enter the gentlecolt’s lavatory. Perhaps it would be best if—”

“Minister, this is police business and you’ve been deputized,” Dupon sighed.

Turing shuffled on her hooves. “Ah, but… that is…”

Dupon shook his head. “Turing… it’s all right, just this once,” he told her gently. “And if you’re worried about your reputation, I assure you, I will not tell any of your friends or colleagues about this.”

“...Very well,” she said. She drew herself up and followed him inside.

Once inside, their hooves echoed on the hard marble floor. The ornate sinks and broad mirrors greeted them, as did several open stalls.

Dupon looked around and saw no way in or out save for the entrance: no windows, no oversized ventilation shafts, and certainly no holes in the wall that a pony could squeeze through.

“If West Walnut came in here, then he could not have left without being seen,” he surmised. “That only strengthens his alibi. Now, then, Turing Test, perhaps we should—”

“Oh my! What are these curious devices on the wall?”

Dupon turned and noticed that Turing was staring intently at the ‘devices’ in question: the urinals.

“Are they some kind of fountain? If so, then my scans indicate they require cleaning. I detect significant amounts of… Oh.” Her pupils shrank. “I believe I have discovered their function.”

Dupon managed to suppress a laugh. “You really are a lady, aren’t you, Minister?”

“My friend Rarity would never forgive me if I acted otherwise while living in Canterlot,” she said, raising her head with apparent pride.

“Well, if you’ve satisfied your curiosity, then could you please examine the stalls here and perform another scan?”

“Understood,” she said.

A moment - and another ding! - later, they had their answer:

“The surface of this commode has traces of digestive fluid on its rim. Additionally there is particulate matter from the Waldorf salad. It is highly probable that this is where West Walnut went when he became nauseous.”

“And did you also find—”

“Traces of the toxin matching the salad?” she asked, her LED eye mimicking a wink. “Affirmative.”

Dupon chuckled. “Then I think we should talk to the kitchen staff once again, and then pay one of our suspects a visit…”

The hotel room door opened and they were once again greeted by a familiar face.

“Well, well, well,” Rio Grand said as she leaned up against the doorframe. “Back so soon? Not that I mind the company, of course.”

“We are dreadfully sorry to bother you, Miss Rio,” Dupon said, “but would you mind if we asked you a few follow-up questions?”

Rio Grand raised an eyebrow and glanced over at Turing Test.

“It is very important,” Turing assured her. “I do not anticipate that we will require much of your time.”

She sighed. “Well, I was about to turn in, but I guess I could have some late night company,” she said. “All right, come on in.”

They entered the little room once again as Rio sat herself down on her bed. “Please try to keep this short, though, huh?” she said, rubbing her neck tiredly.

“We’ll do our best,” Dupon said. “Actually, we neglected to ask you about something else that happened earlier this evening. When West Walnut became ill—”

“Who?” Rio asked.

“The earth pony stallion you followed out of the ballroom shortly before the power surge,” Turing clarified.

“Oh, that old guy?” she asked. Then her eyes widened. “Wait, that was the West Walnut? The guy who owns all those big stores?”

“Affirmative.”

She blinked. “Huh.”

“Something on your mind, Miss?” Dupon asked.

Rio shook her head. “No, sorry,” she said. “Anyway, you were saying?”

“You chased after him when he ran from the room,” Dupon said. “We wanted to know why.”

“Well, he seemed pretty sick,” she said. “I wanted to make sure he was all right.”

“I believe that to be true,” Turing said. “However, he had two guards with him, Mr. Kato and Ms. May Day. Why did you feel that it was necessary to assist him?”

“What, can’t a lady be concerned for somepony else these days without it being suspicious?” she asked.

Dupon narrowed his eyes. “And after you checked on him and saw that he was in good hooves, you returned to your seat?”

“Yeah, that’s right!” she said.

“In fact, Rio Grand, that is not right.” Turing shook her head. “Kato and May Day both stated that you flew in the opposite direction of the ballroom. Later, during the blackout, Gadget bumped into what she believed to be a pegasus mare - most likely you - in the hallway. However, I did not see you return to the ballroom or when I went to investigate the noise outside. In fact, I did not see you until after the body of Beacon Bomber was discovered. You were one of the very last to arrive with the rest of the crowd before Neighstrad declared it a crime scene.”

She slowly trotted around her bed and then leaned in behind her.

“Can you please explain your whereabouts during that time?”

Rio’s calm expression wavered. She began to sweat, and she scratched her neck, squirming uncomfortably.

“I mean, things were all going to Hades in a hay cart, Minister,” she laughed. “I’m not sure I remember exactly.”

“Then perhaps we can help remind you,” Dupon said. “You see, Chef White Heat incidentally mentioned that he took his cooking seriously, as expected, and ignored every ‘crazy fangirl’ that barged into his kitchen. I thought nothing of it at the time, but when I described your appearance to him, he immediately told me that you were in his kitchen before the start of dinner service. You were apparently zipping around, asking everypony about this and that, what they were making and for who, and so on before he finally threw you out.”

“And that was when one of the waiters noted that you lingered noticeably near one of the appetizers. A plate of Waldorf salad.”

Rio became very quiet.

“Strangely, White Heat then mentioned that you returned after the dinner service had started,” Dupon continued. “You were apparently yelling nonsensically at the waiter who’d brought somepony the wrong dish. Quite out of character for a calm, collected pony like you, isn’t it?”

Rio shook her head. “Look, I don’t know what this is about, but—”

“That is another lie,” Turing said.

She winced. “No, see, what I meant was—”

“Miss Rio,” Dupon said gently, “perhaps you should just listen. We said we wouldn’t take much of your time, so allow us to simplify things: you poisoned West Walnut.”

“No! I—”

“Ah, but that wasn’t your intent, was it?” Dupon asked. He shook his head. “No, your intended target was Mr. Vanderbull. You pretended to be an excitable fangirl of White Heat’s just so you could figure out which dish was intended for him. Then you poisoned his food. However, what you didn’t count on was that Vanderbull, a long-time Manehattanite, prefers his Waldorf salad the original way it was prepared at the Waldorf-Wysteria Hotel: that is, without walnuts. The waiter didn’t know that either, and so when Vanderbull refused the salad, it was instead consumed by West Walnut.”

He shook his head sadly. “And you felt so guilty about poisoning an innocent that you impulsively went after him to make certain he was all right. I commend you on your ethics in that case, but if you hadn’t done so and then berated the waiter, we might not have suspected you.”

Rio swallowed. “N-now hold on!” she stammered. “That’s all a bunch of… of hearsay and speculation and… hooey!”

“Incorrect,” Turing said. “Levels of hooey are at 0%.”

Rio glared back at her. “What do you mean?!”

“We discovered traces of a toxic form of latex in the Waldorf salad and West Walnut’s vomit. The substance is milky white in color and visually blended in with the mayonnaise contained in the salad. Such toxic substances are produced by certain plants contained in my database… including the sap of cacti such as the pencil milk bush found in numerous desert regions of Equestria, including Neigh Mexicolt.”

“That doesn’t prove that I put it there!” she cried.

“No,” Dupon said, suddenly seizing the back of her blue bandana and pulling on it roughly. “But this does.”

The knot of the bandana came undone. Rio Grand scrambled for it, but not before both Dupon and Turing saw her uncovered neck.

It was red and mottled with a small rash.

“Inspector Dupon and I both noted that your neck appeared to be irritated,” Turing said. “You scratched at it several times during our interrogation without removing your bandana. We concluded that you smuggled small pieces of the cactus within it…”

“...and judging by this small pouch you’ve sewn into it,” Dupon said, holding it up, “that is just the case.”

“My scans confirm the presence of the same toxin on that bandana. That confirms that you were in possession of it. You had the means, motive, and opportunity to commit the crime.”

Dupon gave her an approving nod.

“Well, Miss Rio?” he asked. “Do you have anything to say for yourself?”

Rio Grand swallowed. “I… I…”

She slumped where she sat on the bed. Then, quite unexpectedly, she began to chuckle.

“Damn,” she sighed. “You know, I didn’t mean to hurt that old bull. It was a weak poison. I just wanted him to be too busy being nauseous to get in the way of my presentation. I could show everypony how great it would be to have that hydroelectric dam in Neigh Mexicolt, get everypony on my side while he was puking his guts out, and finally force him to let us use the land. And also spoil his plans to make even more money by hob-nobbing with all the scientists at the symposium, but that was just a bonus.”

Turing Test shook her head. “You say that, but toxins are often unpredictable,” she said. “You could have caused Mr. Vanderbull great harm.”

“I know, I know, I was just desperate and—”

“Miss Rio,” Dupon said, “we already have your confession. Perhaps it would be best if you saved any further explanation for later.”

“I…” She swallowed. Then she put on a mirthless smile. “I guess Rio Grand is ‘going up the river,’ huh?”

Dupon returned the same sad smile. “I’m afraid so,” he said.

Her lip quivered, and she began to cry. “...Say, uh… is it too late to ask for a fancy lawyer now?” she asked, laughing in spite of herself as she wiped away tears.

“No, but at this point, I suggest any attorney you hire to focus on a suitable plea bargain,” Dupon said.

He drew himself up.

“Rio Grand, you are under arrest for the attempted poisoning of Cornelius Vanderbull and the unintentional poisoning of West Walnut. You do not have to say anything, but it may harm your defense if you do not mention when questioned something which you later rely on in court. Anything you do say may be given in evidence. Do you understand?”

She nodded.

Turing placed a metal hoof on Rio’s shoulder. “Despite your right to silence,” Turing said, “if there is anything you can tell us regarding Beacon Bomber’s death…?”

Rio shook her head. “Sorry, Minister,” she said. “I meant what I said. I had nothing to do with your murder case. After I checked in on West Walnut and yelled at the waiter, the lights went out. I was flying back to the ballroom when I ran into Miss Gadget. I was freaking out at that point and just hid in the hotel rafters. When I saw you, Vanderbull, and then everypony else clear out of the ballroom, I flew back in there, tossed the poisoned salad in the nearest trash can, and then flew out where you all were. But that’s all I know.”

“If that is the case, then we have successfully solved your crime, but made no progress toward our primary objective?”

“Looks like you both missed the main course, huh? As for me… I’m just the leftovers.”

Turing and Dupon were making their way back down the steps of the hotel when Neighstrad came around the corner and met them halfway.

“Chief Inspector!” Dupon said. “We’ve had a breakthrough!”

“You mean you found the murderer?!” Neighstrad cried.

“Negative,” Turing said. “We have yet to discern who murdered Beacon Bomber. However, we have successfully proven that it was Rio Grand who poisoned West Walnut.”

“Ah… well, that’s too bad,” Neighstrad sighed.

“With respect, Chief Inspector,” Dupon said, “poisoning is still quite a serious crime. I’m certain we will have similar success once we solve the murder case. We simply require more time.”

“That’s just it,” Neighstrad sighed. “You don’t have any more time.”

Turing gave a start, her eyes contracting. “Chief Inspector, do you mean—”

“A small boat from the mainland just arrived with a few backup officers and the medical examiner,” he said. “Sorry, Minister, but if you don’t have a different murder suspect for me, then I’m afraid Miss Gadget will be coming with us…”

To be continued…

Author's Note

Enjoying the story? Just a reminder, comments (and guesses in spoiler text) are appreciated!