We still know frustratingly little about what happened to Malaysia Airlines Flight 370, which disappeared two days ago somewhere between Kuala Lumpur and Beijing with 239 on board. But we do know that two (or even four -- some reports say two more passports were "falsely used") of the people on board were using stolen passports to travel. While this may have nothing to do with why the plane (presumably) crashed, it turns out that people traveling using stolen passports isn't all that uncommon.

As both USA Today and the AP reported today, Interpol keeps a database of 40 million passports from 167 countries that have been reported stolen since 2002. Both Christian Kozel and Luigi Maraldi's passports were in that database, and both of their stolen passports were used on MH370. The database was not checked.

Interpol's security general Ronald Noble warned last November that four out of 10 international travelers were not checked against the database. Of the approximately 800 million times it was searched last year, there were 60,000 hits. By that logic, 40,000 people successfully used stolen passports to travel in 2013. 

Yet "unfortunately, few member countries systematically search Interpol's databases," Interpol said in a statement. Over half of those searches come from the United States, the United Kingdom and the United Arab Emirates combined. That's three countries out of Interpol's 190 members. Three.  

Malaysian Prime Minister Datuk Seri Najib Tun Razak said today that the country will "review all security protocols and if needed we will enhance them if necessary."

Thai police are investigating a passport ring that may be responsible for two of the stolen passports. Both Kozel and Maraldi's passports were stolen when they were in Thailand, and the tickets sold to whoever used them were paid for in Thai baht. The tickets appear to have been sold at the same time (the e-ticket numbers are consecutive) and were booked on March 6, just the day before the flight. "Kozel" was supposed to fly to Frankfurt, while "Maraldi" was traveling to Copenhagen.