Russian investigators continue to look for clues in the two airline crashes that killed 89 people, late Tuesday, with terrorism not ruled out as a possible cause. Meanwhile, Russians are observing a day of mourning for the victims.
Investigators are examining the black box flight recorders from each of the two planes, which crashed within minutes of each other as they flew to destinations in the south of the country.
The simultaneous nature of the disasters has led to speculation the planes were brought down by acts of terrorism - either hijackings or onboard bombings.
This theory was bolstered by a report that one of the planes sent out a distress signal indicating that some kind of catastrophic incident was under way, just before it crashed.
However, officials in charge of the investigation have downplayed this version of events, saying they have found nothing, so far, to indicate terrorism might be the cause.
Other theories are mechanical failure, bad weather or that bad quality fuel was loaded onto the two planes, which took off within an hour of each other from the most modern of Moscow's five commercial airports.
Daily newspapers questioned these alternate theories, asking how they can explain two crashes happening at almost the same moment.
Many Russians believe that Chechen rebels may be responsible, given that a Kremlin-backed election to be held Sunday to replace the president of the war-torn region, who was assassinated in a bomb attack, earlier this year. However, the most prominent Chechen separatist leader, Aslan Maskhadov, denies any involvement in the crashes.
Officials say it may be as long as a week before they recover enough data from the black box recorders.
Other investigators continued to sift through the wreckage at each of the crash sites, where the grim task of recovering bodies of the victims also continues.
President Vladimir Putin cut short a Black Sea holiday and returned to Moscow, Wednesday, to meet with Russia's chief prosecutor, as well as with officials who are in charge of the investigation.
Meanwhile, Thursday has been declared a day of mourning for the victims, with flags flying at half-staff and television stations canceling many entertainment programs.