Editor's note: This story contains spoilers for viewers who have not completed viewing Season 7 of "Dexter."
Los Angeles (CNN) -- Showtime made it official Thursday that "Dexter's" eighth season will be its last one, while teasing fans with a video clip from June's season premiere.
Les Moonves, president of Showtime's parent company CBS Corp., had already let it slip in an interview last month that the cable network was pulling the plug on the successful series.
Season 8 debuts Sunday, June 30, the cable network said in a news release Thursday.
The clip posted online "gives fans a sneak peek into the mindset of Dexter and Debra Morgan after LaGuerta's death in Season 7," Showtime's release said.
Debra, Dexter's adoptive sister, killed Capt. LaGuerta in the final episode of Season 7 to save Dexter from being found out as a serial killer.
Dexter tracks Debra down in a grocery store. He tells her he's been worried because she's not returned his calls for weeks and she missed LaGuerta's memorial service.
"Jesus Christ, I wonder why," she said.
Debra tells Dexter she's avoiding him "because you made me compromise everything about myself that I care about, and I hate you for it."
"No, you don't," Dexter replies.
"I shot the wrong person in that trailer," Debra says.
"Dexter" grew into a hit for Showtime since its debut in 2006, both with ratings and awards. The show won a Peabody while earning 25 Emmy nominations.
"'Dexter' redefined the genre, by taking the anti-hero to new heights and pushing the boundaries of the television landscape," Showtime chairman Matthew Blank said. "Dexter paved the way for the next generation of award-winning hit Showtime series, and its cultural impact will be felt for years to come."
Showtime is adding a new original series, "Ray Donovan," to replace the popular "Dexter," Moonves said.
Liev Schreiber will star as a "fixer" for Los Angeles' rich and famous set.