(I didn't find too much info about Petersen online but interested parties can read a brief bio and overview of his work here.)
(ETA: Cover by George A. Frederiksen / Mapback by Ruth Belew; thanks to UK Vintage for the info.)
As of today I'm unsure whose hand is responsible for drawing the bony hand (and arm etc.) seen on the front cover - or for that matter who drew the crime map on the back - but, as always, if / when I get any additional info. I will add it in.
(PS: Larger versions, as well as covers of books that have found their way on to the blog previously, can be seen in the Pulp Fiction Project set in my Flickr photostream, here.)