Did you think they just fucking disappeared into thin air? They were working with the Female Titan spy.

[and they are people Jean knows, possibly had even befriended. Still, (or rather, because of this), Levi won't divulge those identities to Jean quite yet. Other details likewise aren't quite necessary at this point.

Except for perhaps one other fact:]

I also formed a new squad from the remaining 104th top recruits - which includes you, so don't think that this place is some kind of freaky vacation from reality.