I work as a UX researcher at a mid-size tech company. Not huge, not startup-chaotic, just like 200 people, open floor plan, the usual. My coworker Marcus has been on the team about a year longer than me and we always got along fine. Or I thought we did.

It started last August. I was leading a usability study for a product redesign — big deal, director-level eyes on it — and when I pulled up my synthesis doc the morning of the readout, half the affinity clusters were just gone. Like deleted. I panicked, rebuilt what I could from memory and raw notes in two hours, presented something half-baked, and basically got told to "sharpen up" by my manager Dana.

I figured I'd accidentally saved over the file. These things happen.

Then in October, same thing. Research report due for a quarterly review. I'd finished it the night before, I remember closing my laptop thinking okay, this is actually solid. Came in the next morning and the document was a two-page skeleton. No findings, no recommendations. Just the title page and a placeholder table.

Dana pulled me aside after that one. She was nice about it but she said, "I need you to be more on top of your deliverables. This is the second time." I wanted to crawl into the floor.

I started keeping local backups after that. And for a while nothing happened and I thought okay, operator error, lesson learned. But in January it happened again — except this time it wasn't a missing doc. It was a mislabeled one. My participant recruitment screener had the wrong study criteria in it, so we screened in completely the wrong users and the whole study had to be scrapped. I was so confused because I remembered writing those criteria myself.

That's when I started paying attention in a way I hadn't before.

The thing about our office is that people hot-desk. Assigned spots are technically a thing but nobody enforces it. Marcus sat near me maybe three or four days a week. I'd never thought anything of it. But I started noticing that on the days before a major deliverable was due, Marcus would always end up at the desk right next to mine. Always had some reason — "better monitor," "closer to the window," whatever.

I mentioned it to my friend Priya who works in product. Just venting over lunch. And she said, "wait, does he know your computer password?" And I was like — we'd paired on a doc together months ago and I'd logged into my account in front of him and he'd commented that I use my dog's name as a password which I laughed off. So. Yes. Apparently he did.

I want to be clear that at this point I had no proof. I had a suspicion and a bad feeling and a pattern that could have been coincidence. I also genuinely liked Marcus. We'd gotten drinks with the team, I'd covered for him on a deadline once. So I sat with it for two weeks being like, am I being paranoid? Am I being unfair?

But I kept coming back to the screener thing. Because that wasn't a deleted file. That was a changed file. Someone had edited it to say the wrong thing. That's not an accident I could have made.

So I set something up. I had a big competitive analysis due March 3rd. I finished it on the 28th, backed it up three different ways, and then — and this is the petty part I'm not proud of — I intentionally left a version open on my work laptop that looked like the final version but was actually just a placeholder. Different filename, same spot in the folder. And I changed my actual password but left the old one working on just that one decoy document through a share link trick our IT guy helped me set up without knowing why I needed it.

Then I put a keylogger notification on the decoy document. Anything that opened or edited it would ping me.

March 1st, 11:47pm. I'm home watching TV and my phone goes off.

The document had been accessed and edited. From the office. From my login.

I screenshot everything, forwarded it to my personal email, and then I sat there for like ten minutes just feeling sick. Because I wasn't happy. I really wasn't. I kept thinking about every time I'd defended Marcus when other people on the team complained about him and I just felt like an idiot.

I brought it to HR the next morning with Dana CC'd. Showed them the access logs, the keylogger notification, the timeline of every messed-up deliverable matched against his desk location records. HR was quiet for a very long time.

Marcus was walked out four days later. I don't know exactly what was said to him. I was not in that meeting.

Dana came to me afterward and said, "I owe you an apology. I should have asked more questions." I said "it's okay" because what else do you say. It's not really okay, eight months of my performance record have a shadow on them and I don't know how long that follows me. I asked about getting those reviews formally reconsidered and HR said they'd "note it in my file" which, great.

I found out through Priya that Marcus told a mutual contact I'd "set a trap for him." Like that was the unfair part. Sure man. That was the problem here.

I still use my dog's name as my password. I'm not changing everything about myself because of this guy. I did change my dog's name though. She's Rutabaga now. She doesn't seem to mind.