Simultaneous Publication in Different Venues

You are the editor of a yearbook summarizing recent research in your field.  One of the main articles was submitted by a colleague, who is cited among your coauthors.  Several months after your book was published, you see an article by that colleague in a peer-reviewed journal.  Although dealing with the same subject matter, this article is entirely different from the chapter in your book.  You notice, however, that two illustrations--a graph and a diagram--are identical in both.  Neither publication acknowledges the other.  You later learn that the article was prepared and submitted to the journal before your book was written, although it did not appear in print until after the book was published.  What, if anything, should you do?