Supernatural's Gabriel will dish out drugs during CSI's "Buzz Kill."

CSI: Las Vegas kicked off season 15 with a return to D.B. Russell's (Ted Danson) Gig Harbor Killer, but the CBS drama will take on a drug-fuelled kidnapping for the season's second episode.

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"Yes, my CSI airs next week (glad I got a reminder tweet)," Speight tweeted on Monday ahead of his appearance as Lloyd Bryant, the owner of a medical marijuana clinic .

For those fans eager to learn more about the Gig Harbor Killer and the Winthrop twins (Mark-Paul Gosselaar), they can rest assured that the rest of season 15 will pack in much more of the murderer's storyline starting in episode 6.

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"The #GigHarborKiller storyline will be revisited in episode 1506," the CSI Writer's Room confirmed on Sunday.

Meanwhile, viewers can tuck in for a darker season than ever.

"We're very excited about what we have planned for you this year. It's super dark and twisted," tweeted the CSI Writers' Room in early June, later reassuring viewers that the season will be "not painful at all! It will be a fun season (and dark), but not painful. Fun!!! :)"

Find out more when CSI airs Sundays on CBS. Click the video below to see a preview of "Buzz Kill."

Tags: CSI: Crime Scene Investigation television CBS