The actor also discussed his next role, a cop in pursuit of Charles Manson, in advance of the 'Californication' series finale

With the series finale of Californication airing this weekend, David Duchovny says he feels like he has comfortably closed the book on his character Hank Moody. That's not the case, though, for another one of his iconic characters: The X-Files' Fox Mulder. During an in-depth interview with Rolling Stone about the end of the long-running Showtime drama, which will run next week after the finale, he said that he would be up for making a sequel to the 2008 movie The X-Files: I Want to Believe.

"I would always want to do it," he said. "I wish we'd done more already. I wish the second one did better business. I think it did OK business, but not the kind of business where you get to do another one right away."

Duchovny said that he remains friends with both X-Files creator Chris Carter and his costar, Gillian Anderson. Moreover, he loves the Fox Mulder character. "Once I was able to branch out and do some other movies and do Californication, I didn't feel like, 'People only think I do that,'" he said. "I no longer have that anxiety."

Ultimately, the possibility of making a third movie – for which he said no script exists ("I'm friends with Chris, and I'm sure he would have said something") – depends on a number of factors. "It's just a matter of interest from Fox and scheduling," he said. "Chris has got a new show. Gillian's working. I'm working. It's not impossible, but it's not easy. And I never think it's done. I'd say, it's never done until one of us dies – until one of us three is gone."

In the immediate future, Duchovny is prepping for his role as Sam Hodiak in the crime drama Aquarius, which will air on NBC some time next year. The show takes place in Los Angeles in the late 1960s and follows Hodiak, as he attempts to solve a murder and finds his way to Charles Manson. "My character is trying to find a missing girl, a daughter of a friend of his," he says. "I play a straight-up Fifties man being introduced to the new world of the Sixties and Manson, and the world is changing all around me and I'm not able to change with it."

"It's a very interesting time period for the country," he continued. "Still, to this day, there's a lot of mystique about the promise of the Sixties and what went wrong there and what's gone wrong since. You had Manson on one hand, and the dark side of the Sixties, and you've got peace, love and Flower Power on the light side. There's a lot to work with."

Shooting for the show has not yet begun, so Duchovny has been spending his time prepping for the role. "I talked to homicide detectives to get a feel for what their day is like, for what their job is like, so I can feel comfortable physically in the world," he said of his process. "After that, then you're playing a character. You want to make somebody new."

Duchovny says one of the main things that drew him to the character was just how different Hodiak was from Californication's Hank Moody. "And I think Moody was as far from Mulder as I could get," he said. "Whereas Mulder could have been a virgin – we're not sure – Hank Moody certainly was not. And this cop, he's not Robocop, he's not completely straight-up; he's got his demons but it's a different world, it's a different style of acting. It's going to be very different. I like the challenge."