Ayo

Something similar happened to me too.

I was testing out a new Nodegraph i made for the map since the current one isnt all that good.

To test it i spawned NPC rebel's in parts of the map, tested if they used the nodegraph correctly, despawned them and repeat.
When i spawned them in the small 2 office boxes with the ticket booth windows in them, something weird happened.
I use the Holographic Hud thing which has the radar and on the radar a dot suddenly showed up, i didnt spawn it it just was there- and moving.
On the recording i could see that it was a Civilian npc holding a camera. It followed me but before it reached me i noclipped out of bounds. After that it was gone. I tried to replicate this but i cant get any results.

Try spawning multiple nextbots, then watch the nextbots where they will go. This way you could find him, or maybe kill him.