I need to communicate the fact that a co-worker is no longer engaged on a task, normally communicated as below:

> [Customer], [Coworker] had to leave the office early today, so I'm
> taking over for him.

However, [Coworker] was never even in the office because he was working from home.  Is there a word (or phrase) for the idea "leave work early" that doesn't use the idea of location?  Everything I've come up with seems clunky or incomplete. "Stop work" has some pretty negative connotations in my industry, so I need something else.