It's surprisingly easy to miss a dead person, it's not like they have a pink neon "HEY I'M BEING DEAD OVER HERE".

> However, that office supposedly has round the clock security, and the security on duty didn't pick up on anything unusual.

I can imagine that if I had the security officer's job, and I walked around same office every single day, I'd really stop caring at some point and could potentially miss a dead body. It's an office, not airplane landing checklist after all. Probably the guy was looking for things like open doors or damaged equipment.