co-worker again

We had two programs to adjust; in two weeks, he adjusted half of one program.

I got it working and over the line, just today. Now I'm working on the second program and discover he hasn't done any changes to it...

Also: getting these two programs working has happened in between other work I've been doing for the client - while transferring files and answering questions and trying to work out scenarios and where files are going.

...what on earth was he doing for those two weeks?!?