As the coronavirus pandemic sweeps through the country, panic and fear have caused a run on hand sanitizer, toilet paper and guns. Retailers tell us they have never seen such a surge in firearms sales. One kind of weapon that has been selling out is a build-it-yourself firearm known as a ghost gun because it skirts most federal gun laws. There’s no background check and no serial number, making ghost guns invisible to police and almost impossible to trace when used in a crime. We were surprised that it’s all perfectly legal. After a year and a half of reporting, we discovered that ghost guns, once mainly popular with gun enthusiasts, have also become a weapon of choice for criminals, manufactured by gangs and used in mass shootings.