By now, it should all have been over for Sci Fi Channel's "Battlestar Galactica" -- filming wrapped, cast and crew scattered, episodes working their way through the post-production process.

But thanks to a three-month shutdown for the Writers Guild of America strike, this week instead marks the beginning of filming for the final group of episodes in the fourth and last season of "Galactica."

"It's still the last season," star Katee Sackhoff says. "It's just taking a lot longer to shoot the dang thing than we thought it would."

On Friday, March 28, Sci Fi airs two half-hour specials to launch the first half of the 20-episode season, which starts airing April 4.

In "Battlestar Galactica: Revisited," executive producers Ronald D. Moore and David Eick lead a condensed journey through the show's first three seasons. In "Battlestar Galactica: The Phenomenon," celebrities including Seth Green, country singer Brad Paisley and "The Soup" host Joel McHale reveal their love for the series.

Talking about the abrupt end to shooting last fall, Moore says, "We were starting to get wistful and feeling senior year-itis, as we approached the midseason point. Then the strike swamped everything else.

"If you talk to the cast and the crew, they went through a lot of emotions when they were shooting the last episode that we shot. They were feeling like they were saying goodbye to the show."

"I was trying to be the complete optimist," Sackhoff says. "I had to counteract Aaron Douglas, who was a pessimist. He's sending all these e-mails, 'We're never going to see each other again.' So I was like, 'This is crap. We're coming back.'

"So I was trying to keep the crew and the rest of the cast motivated. 'It's OK, guys, it'll just be a while.' Of course, I was like, 'It'll be a week. No problem.' Yeah, well, I was wrong about how long it would last, but I knew we'd be back."

As season three ended, the world of "Galactica" was turned upside down. The story centers on a hastily assembled fleet of spaceships, led by the Battlestar Galactica, carrying survivors of a devastating attack by the mechanistic Cylons on the 12 colony worlds that were home to their human creators. Leading the fleet are military Commander William Adama ( Edward James Olmos) and civilian President Laura Roslin (Mary McDonnell). The goal is to find the once-thought-mythical 13th colony -- Earth.

Having evolved to where they can mimic human form, the Cylons have relentlessly pursued and infiltrated the humans, even getting to the point where a Cylon successfully interbred with a human. But they are still artificial creations, with all humanoid Cylons based on 12 original models.

Seven had previously been revealed -- including a Galactica officer ( Grace Park) and a reporter ( Lucy Lawless) -- and in the season finale, four unsuspecting people discovered, to their horror, that they had been Cylons all along.

They were Galactica's second-in-command, Col. Tigh (Michael Hogan), resistance leader Sam Anders (Michael Trucco), Chief Galen Tyrol (Douglas) and political adviser Tory Foster (Rekha Sharma).

The identity of the 12th and final Cylon has yet to be revealed.

Also at the end of last season, Sackhoff's character, fighter pilot Kara "Starbuck" Thrace, apparently returned from the dead, claiming she had seen Earth. In addition, in a two-hour "Battlestar Galactica" movie, called "Razor," aired last November, an aged human/Cylon hybrid offered dire warnings about the apocalypse to follow if humanity followed Starbuck's lead.

Naturally, her sudden reappearance raises doubts about who -- or what -- Starbuck may be.

"They thought she was dead," Sackhoff says, "and now she's back, which in everyone's mind says 'Cylon.' If we look at past shows, how do they treat Cylons? They airlock them.

"So, that's where we come in, with Starbuck getting the rare, beautiful treatment of a Cylon. It's fantastic."

Regarding whether or not Starbuck may indeed be the 12th Cylon, Sackhoff says, "I have no idea. I wish that I could say that I've got some insight into what's happening, but no one tells me anything."

Sackhoff does, though, have some ideas on how she'd like Starbuck's tale to end, saying, "Starbuck would not be happy unless she walked off into the sunset by herself. That's just who she is. That's her pain. That's her cross to bear. So we'll see."

There always was a plan for Sci Fi Channel to split the airing of the final 20 episodes in two. But, because of the break in production, Moore and his fellow writers have had an opportunity to rethink a lot of decisions they made early on about the back half of season four (the airdates for which haven't yet been determined).

"We decided to revisit some of the episodes that we broke before the strike," Moore says, "and thought, 'No, we're going to change our minds about that.' We had some time to think about things. Some of the things we were planning weren't working as well, so we had a chance to reassess."

As to whether he's happy about this, Moore says, "Yeah, I'm happy that we got a chance to revisit things. Typically the writers don't get a break in the middle of the season to re-evaluate. You make a lot of decisions about where you're going, then you get really focused on getting there.

"The strike gave us a chance to step back and look at the big picture a second time, which is a luxury that you don't usually have. I know that it's going to be better as a result."