The co-showrunner of "Castle," has left the series after failing to reach a new deal with ABC Studios, reports Deadline.com.

It’s Rene Echevarria, who had earlier served as an executive producer of "Medium" when it was on NBC. Echevaria  is working on other projects including MTV’s pilot "Teen Wolf."

Andrew W. Marlowe, Castle’s creator who served as executive producer and co-showrunner with Echevarria, will remain as the program’s sole showrunner. "Castle" is one of ABC’s best up-and-coming shows and has earned an early renewal for next season after pulling in higher ratings.