With a subject who's dead and buried, using known images of the person to create a caricature from wouldn't be plagerism if the images he's working from aren't caricatures.

Ok, so I can take a photograph of your grandfather, distort it a bit (I'll just use Photoshop to save time) and sell it as a caricature.

The connection is that the "caricature" is an original painting / photograph that has been altered very slightly. Take a look and compare the drawings to the originals, you know, practically every single part of the original is duplicated except for the malformation of small accentuated areas. It would be the same as changing the cover of the DVD.

What is rather interesting about this discussion is that it has drifted away from what constitutes a good caracature (Look at Zapiro's work) to copyright, plagerism & piracy.

A good caricature is not dependent on an original work of art or photograph to give it credibility, it is dependent on the artists ability to accentuate a feature of the person being drawn yet leaving enough resemblance for the audience to recognize the person. Zapiro is a master at this - Zuma with his showerhead, Obama's ears, Mugabe's upper lip, Trevor Manual's nose, etc.