Federal investigators know the identity of the bomber, a 20-year-old native of the volatile Caucausus region, where Islamist insurgents have been battling for years for a breakaway state.
But the country's top investigative body stopped short of naming him, fearing that it would compromise ongoing attempts to identify and arrest the masterminds of the Domodedovo Airport attack on Jan. 24. The blast also wounded 180 people.
There has been no claim of responsibility, but security analysts suspect Islamist separatists of organizing the bombing because of its magnitude and method.
"It was no accident that the terrorist act was carried out in the international arrivals hall," federal investigators said in a statement. "The terrorist act was aimed first and foremost at foreign citizens."
The victims were mainly Russians, but also included one person each from Britain, Germany, Austria, Ukraine, Tajikistan, Kyrgyzstan and Uzbekistan.
The violence stemming from the predominantly Muslim Caucasus region originates from two bloody separatist wars in Chechnya in the past 15 years. Federal forces wiped out the large-scale resistance, driving the insurgency into the mountains and into neighboring provinces. The rebels seek an independent Caucasus emirate that adheres to Shariah law.
Caucasus rebels have claimed responsibility for a number of deadly attacks over the years, including a double suicide bombing on the capital's subway system in March 2010 that killed 40 people. One of the subway stations hit was under the Federal Security Service headquarters in downtown Moscow. The service, the main successor to the feared Soviet KGB, is known by its Russian language acronym, the FSB.
This time, the terrorists are out to show that it's not just the Russian public who are defenseless, said Pavel Felgenhauer, an independent security analyst.
"There is always a message," he said. "If the message with the metro bombings was to show the FSB that they are not out of reach, then the message here is that foreigners should keep away from Russia, it's a dangerous place. The point was to scare off foreigners, not to maybe kill them but to hit Russia's image, (and) its economy as an investment destination."
"Looking at Medvedev's reaction, it seems that point got through," Felgenhauer said, referring to President Dmitry Medvedev, who postponed his trip to the World Economic Forum in Davos because of the blast. When he eventually arrived on Wednesday, Medvedev condemned the perpetrators and sternly defended Russia as an investment haven.
Rebels in the Caucausus mount regular attacks on police and security forces in the region, according to police reports. Human rights activists say their violence is provoked by a savage crackdown on peaceful civilians by authorities in the region, and hold Chechen President Ramzan Kadyrov and his feared private army to blame. Kadyrov, a former rebel himself until he switched sides and was subsequently installed by the Kremlin as president, denies being behind disappearances, torture and extra-judicial killings that rights activists say plague the region.
The Caucasus hosts at least 100 ethnicities including Chechens, who resisted czarist conquest of the region for hundreds of years.
Since the blast at Domodedovo Airport, a half-dozen transport and police officials have been fired. Medvedev said after the blast that Domodedovo's security was in a "state of anarchy."
Russia's parliament has given preliminary approval to a law creating color-coded terrorist threat alerts, a measure rushed forward in the wake of the airport bombing. The proposed law is modeled on the U.S. system instituted after the Sept. 11 attacks, which Washington announced Thursday it would be abandoning by the end of April and replaced with a new plan to notify specific people about specific threats. Critics had complained the general color alerts were unhelpful. Russia's State Duma, or lower house, unanimously approved the bill Friday in the first of three required readings.
The explosion also called into question Russia's ability to safely host major international events such as the 2014 Winter Olympics and the 2018 World Cup, events designed to attract foreigners and their investment capital, to Russia.