The illos here show the cover art for the six volumes I have, as well as a B&W of the seventh book's cover- which I have yet to see in my local bookstore. The cover art for books 1,2,3,4, and 6 that I have are by Vito DeVito and the cover art for book 5, being a second edition I think, is by Fred Gambino. I have, as of yet, no idea who did the cover art for book 7.
The series started in March of 1990 with "Bloodlist"and was quickly followed by June of 1990's "Lifeblood"...
Continued with "Bloodcircle" in October of '90, "Art in the Blood" in Febuary of '91,
"Fire in the Blood" in June of '91, and "Blood on the Water" in June of '92.
The next in the series, "A Chill in the Blood" will, I assume, be released (soon) in '99.