The news anchor mentioned a recent bank robbery apropos of

I believe the answer is: tighter security being announced.

In journalism, apropos is used to make a reference of past event, which would make the information that they deliver next making much more sense. In the example above, the robbery is referenced to tighter security to make the audience the motive/reason behind the tightening of the security.

The news anchor mentioned a recent bank robbery apropos of tighter security being announced.