~from Levi's POV~
I was starting to get an idea. Well, two, really. Or rather, a combination of ideas.
Someone else was in the park.
It was nearly undeniable. No one person could have committed all of those crimes. They either didn't have the opportunity, or they didn't have the motive.
Which meant there was someone else.
Which didn't mean there wasn't still a murderer in the camp.
When one dead body showed up, it would be natural for them to turn on each other.
In other words, I might be looking at multiple murders, as well as an outside job. Possibly.
Also possibly, the murderer could be working with the outsider, if they did indeed exist.
Something I'd thought about earlier caught my mind, back when I was thinking about Marco and Jean. Killing your best friend would definitely put you out of suspicion, at least at the immediate moment.
And if you were out of suspicion back when I assumed there was only one killer, you were assumed to be innocent for all of them.
What if that wasn't the case?
If it was a two-man job...
I turned toward the door and left the arcade.
There was someone I had to talk to.
***
I found Eren back in our tent, where he'd presumably never left.
"Hi, Levi," he greeted, his eyes still red from crying over Armin. "Anything happen?"
"Yes, something happened, Eren. You killed Armin."
"What?! No! I didn't! Why would I kill my friend?!" After a moment, he stared at me with betrayal in his eyes. "You don't trust me, Levi?"
"Trust doesn't matter. What does matter is that you're the most likely suspect primarily because killing Armin made you the least likely suspect."
"What?"
"It's why Jean was an unlikely suspect - because of Marco. His death was fairly violent, wouldn't you say? Electrified. But Armin died fairly peacefully. Like the killer didn't want him to suffer. Like you didn't want him to suffer."
Eren was crying by this point. "I swear, I didn't kill Sasha or Marco!"
But you did kill Armin."
Eren closed his eyes. "I...I didn't want to. But I had no choice."
"Why not?"
He opened his eyes. "I was protecting someone else."
"The other person in the park, the one that we haven't seen yet," I finished for him, and his eyes widened. "Now, who could possibly be more important to you than one of your best friends, Armin?" I halted my thoughts for a second. "Hang on. You're also the person who found (y/n)'s cell phone."
He paled. "I did."
"Of course you did, because you're the one who buried it."
He grew even more pale, his bright green eyes providing contrast. "I...I was never going to kill (y/n). I swear."
"You killed your best friend. Who's to say that you wouldn't kill some girl you barely knew?"
"Because! I just wouldn't. I can't kill (y/n). And I didn't want to hurt Armin either."
"You didn't hurt him, Eren. You killed him."
"I know," he whispered, crying again. "But I wasn't going to kill (y/n). The plan was to bury her phone near her tent, then have you look at Armin, and then we'd go over to (y/n)'s tent. I'd find her phone and save the day. She was never going to die, Levi. I swear."
"So you almost killed a second person to make you look even more innocent after the first person you killed? Eren, you're a psychopath."
"No! I'm not! I didn't hurt (y/n)-"
"No, but she could barely breathe," I snapped, smacking him across the face. Kind of like how (y/n) had slapped me. I had deserved it. "She was suffocating, Eren. She was turning blue because she didn't have enough oxygen because you BURIED HER ALIVE."
Eren was still stunned from the smack, but he dropped his head when he heard me. "I'm sorry, Levi. I'm so sorry. I..."
"Shut up. Did you kill Erwin too?"
"Erwin? Erwin's dead?"
"Don't play the innocent game with me. You've played it long enough. Just tell me if you killed Erwin."
"N-no, I swear-"
"Your word means nothing. Your actions have spoken loud enough. Now tell me something, Eren. The person you killed Armin to protect - is that the person who killed Sasha and Marco?"
He refused to nod or shake his head.
I kicked him in the stomach and forced him to look up by grabbing his hair. "You owe me, Eren. And now's the time to start talking. Did they kill Sasha and Marco?"
Still, no confirmation nor denial.
"I'll take that as a yes." I stood up. "I have an idea about why you killed Armin. He had figured some of it out, hadn't he? Or he had at least known that there was one more person in the park. And he brought his suspicions to you, his best friend. Maybe he even had some sort of proof; I don't know. But either way, you knew that it was too risky to let anyone else know, so you asked to see his phone for a second, and then you placed it in the puddle and watched him die."
Eren was crying once more, but he wouldn't say anything.
"Keep protecting her, Eren. Watch as all of us die because of you." Then I left the tent and found Kirstein waiting outside (y/n)'s tent.
"Well?" he asked.
"I know who's in the park, and I know who killed Sasha and Marco." I would share about Eren later. There was more important business right now. "Any change in (y/n)'s condition?"
"None." Kirstein looked grim. "Is that a good thing or a bad thing? I can't help but be paranoid about it. Of course, maybe something weird happened, like I put her phone down in the wrong place, and it's actually fine."
"We both know that didn't happen. But at least she's alive for now."
Jean nodded, sighed, and faced me. "So who's the killer?"
"Eren's sister, Mikasa."

A/N: so, originally, Eren was the only killer, but then I read some readers' comments, mashed a few ideas together, and...well...this should be interesting. Hope you guys enjoy :) it's almost the end.
Thanks again to all the readers who commented (and who I may have lowkey stolen ideas from)