http://www.chinapost.com.tw/i_latestdetail.asp?id=22624
Russian officials also announced that they were investigating the backgrounds of two female passengers with Chechen names who booked tickets on both flights at the last minute and who were the only victims whose relatives have not contacted authorities.
Paul Duffy, a Moscow based aviation expert, told Associated Press Television that he found it "hard to believe" that five attackers were aboard each plane "but there is no doubt that they had one at least on each aircraft."
In the Russian media, suspicion focused on two women passengers, identified as Amanta Nagayeva and S. Dzhebirkhanova. Nagayeva, a Chechen native, bought her ticket one hour before the Tu-134 departed, Russia's NTV television reported. She was seated in the rear of the plane, near the tail which was found severed from the rest of the fuselage at the crash site. Search crews found fragments of her body on Friday, according to Russian news agencies.
The other passenger had originally been scheduled to fly to the Black Sea resort of Sochi, where Putin was vacationing, on a morning flight, but she changed her ticket at the last minute, according to the Gazeta.ru Web site.
Female suicide bombers with alleged Chechen connections have carried out attacks in Moscow, including last year's twin bombing of an outdoor rock concert and another blast outside a hotel adjacent to Red Square.
There was some speculation that the bus stop bombing that same day may have been a bomb(er) who couldn't get to his/her flight and so detonated at the bus stop.
[Remember on 9-11 there was specualtion of other teams that failed to attempt their hijackings. We still don't know what was actually in progress that day. The radicals wanted to hijack up to 10 planes that day. It would have been much, much worse than it was.]
So why not five? With five, the terrorists have many more options. For instance, let's say that one is discovered prior to the flight taking off. The authorities pat themselves on the back falsely believing that they've just prevented a bombing. But it still leaves four to carry out their "mission". Like Duffy said: "...there is no doubt that they had one at least on each aircraft."