How is “shifting” supposed to work in Death Angel?

Question

I've read and re-read the rules for shifting marines, but I'm still completely baffled as to how shifting is supposed to work in Death Angel.

This evening I had the following setup:

Dark Corner - Brother Claudio - Ventilation Duct - Genestealer
       Door - Brother Zael    - Corridor
              Brother Goriel
              Brother Noctis
              Brother Omnio

I used Brother Claudio's "Heroic Charge" attack, and since my die appears to be loaded, I rolled yet another 0 and Brother Claudio died.

The rules for shifting state:

Shifting is resolved by taking every Terrain card, Space Marine card, and Genestaeler card in the smaller segment of the formation and moving them up or down to fill in the slain Space Marine's previous position.

The smallest segment is defined as the half of the formation that contains the least Space Marine cards. If both segments of the formation are even, the bottom segment is shifted up.

So once Brother Claudio dies, I'm left with this:

Dark Corner - ??????????????? - Ventilation Duct - Genestealer
       Door - Brother Zael    - Corridor
              Brother Goriel
              Brother Noctis
              Brother Omnio

Question 1: When are the formation halves determined, before or after the marine dies? And what happens when you have an odd number of marines, what exactly is a segment? And in this case, does it really even matter?

Question 2: Should (1) the Dark Corner, Ventilation Duct and Genestealer from Claudio's row shift down to Brother Zael, placing the Dark Corner and Door both on Zael's left, and the Ventilation Duct, Corridor and Genestealer on the right?

Door / Dark Corner - Brother Zael    - Ventilation Duct / Corridor - Genestealer
                     Brother Goriel
                     Brother Noctis
                     Brother Omnio

Or (2) should Zael shift up to where Claudio was, Goriel shifts up to where Zael was, and Noctis and Omnio stay where they are, leaving the formation as follows:

Dark Corner - Brother Zael    - Ventilation Duct - Genestealer
       Door - Brother Goriel  - Corridor
              Brother Noctis
              Brother Omnio

Can anyone more clearly sum up the rules for shifting?

Answer 1

by my understanding...

the halves are determined by looking at the space left by the dead marine. So it's after removing him.

I believe that, yes, when claudio dies in your example, the terrain all winds up at the front.

Answer 2

Mostly posting to agree with aramis, but adding in a couple links.

• Official Rules
• Condensed Rules

As to your first question, I think the wording on page 27 shows the shift (which includes figuring out the larger side) takes place after removing the slain marine:

If a Space Marine is slain (usually by being attacked by a swarm), his card is removed from the formation and returned to the game box. The formation will then need to be shIfTEd (see page 28).

On page 28 of the official rules, it states:

Shifting is resolved by taking every Terrain card, Space Marine card, and Genestealer card in the smaller segment of the formation and moving them (up or down) to fill in the slain Space Marine’s previous position.

and

When shifting, note that it is possible for more than one Terrain card to be in the same position.

From the example on page 29, it's clear terrain next to a slain space marine in the middle of the formation would stay where it is, and have things moved to it, but in your example the only place for the Corner and Duct to go is down, to Zael's position. Moreover, I believe that first quotation makes it clear the Door and Corridor would stay on Zael's position.