A common question fans are asking is whether D'Anna Biers is lying when she says that there are four of the final five with the fleet, and one (the mystery Cylon) is not. They want her to be lying, because her statement rules out so many popular fan choices for final Cylon, such as Gaeta, Dualla, Cottle, Lampkin and Zarek. It also rules out choices for people who don't buy the declaration that the final Cylon is not in the Last Supper photo, such as Apollo, Starbuck and possibly Adama, who is on Galactica when she again declares there are four.

D'Anna has her own agenda that we don't yet know. So she certainly would have no problem lying if it suited her purposes.

But a harder question is, how would she know to tell this lie? She knows the identity of the final Cylon. But there is no reason she should know that the final Cylon is different from the other 4. The only people who know that are the 4 themselves, and perhaps the one. In fact, the four didn't know anything back when she got her vision of them in the Temple of Five. (What the one knows, we don't yet know, but it is strongly suggested they were also a sleeper, and may still be a sleeper, in that they are described as "still in shadow.")

There seems no way that she could know that one is different, and thus to ask for four. Unless she knows the fifth is not with the fleet, which would mean:

• The fifth is somebody she knows to be dead (like Elosha, Joseph Adama, Zak or some others.)
• The fifth is somebody with her on the base star (like Helo, Adama, Roslin, Baltar or Seelix.)
• The fifth has some other unknown attribute that lets her know where he/she is.

She knows the fifth person, since we in the audience have been assured we will know him/her.

Then there are characters who died while she was boxed, such as Cally, and there's Starbuck who "died" while she was boxed. She would not know directly of this. For her to know, the Cylons on the base star would need to have found out about these deaths from the crew, and told her. This is possible, of course, but it seems unlikely with the distrust. Military crew should not be getting chatty and blabbing intel to the Cylons. But they might have.

But again, nothing we have seen gives her any ability to know that one is special. Which makes it very likely that she has found out through one of the reasons listed above. I don't know what the unknown attribute could be, but of course the writers could make up something. Like her seeing the 5th in special robes, or them having a metal robot face, perhaps. Or the face of the Hybrid, though I don't see that as likely.

I should point out that she doesn't say that the fifth is not with the fleet. She justs states that four are with the fleet. She says nothing about the fifth. So the implication (5th not with the fleet) is strong but never exactly said. However, if the fifth is with the fleet, and she tells them she is going to collect four, it means she somehow knows the fifth is different, and won't be coming when she goes to get the four. It's hard to see who this fifth could be, with the fleet but not going to be coming in her view, or with her knowledge. For those of you sure it's Gaeta, Dee or Cottle, how does she know they're not going to be collected?

It's really clear she plans to collect only four, no matter what she knows. She plays a deadly game of hostage-executing brinkmanship with Lee Adama, while demanding only four. In fact, she targets nukes at the Civilian fleet as part of this standoff. She tells Baltar if the 3 are executed "the whole human race dies with them" indicating she would also attack Galactica. If the fifth is in the fleet, it does not make sense for her to nuke it.

I do feel, though we as yet have no evidence for it, that it was the fifth to whom she apologized so profusely. It could have been any of them, but somehow I think it was the fifth.