Meaning of "at the paper"

“I think the people at the newspaper have been putting me off for the last couple of days,” said Iskender; “that’s why I resorted to calling you. For the last two days Jelal hasn’t been at the paper. Something must be going on.” – The Black Book by Orhan Pamuk

In this story, Jelal was a columnist. When it says Jelal hasn’t been “at” the paper, does it mean he hasn’t been to his office or his column hasn’t showed up?

I would understand that Iskender has been told (for the last few days) that Jelal isn’t in the office, apo.

Yes, ''hasn’t been at the paper" means he hasn’t been to his office. (Maybe he doesn’t even work there any more.)

"Jelal hasn’t been in the paper’’ means that his column hasn’t been in the paper.
This sentence is short for “Jelal’s column hasn’t been in the paper”.