A U.S. aviation expert close to the investigation told CBS News officials are convinced an IED inside a laptop caused the midair explosion that forced a passenger jet to make an emergency landing in Somalia.
The expert said investigators were also working on a theory that a guard was likely bribed to slip the device past security and onto the plane.
Shortly after the pilot safely landed the Daallo Airlines Airbus 321 carrying 74 passengers Tuesday, officials called the explosion a bombing, based initially on scorch marks found on the headrest in front of the seat where the explosion left a gaping hole in plane.
A law enforcement source told CBS News senior investigative producer Pat Milton that the FBI is sending a team to Somalia to assist in the investigation.
Somalia's government confirmed Thursday that a passenger who had been missing since the explosion had died. It identified him as Abdullahi Abdisalam Borle, but gave no details about how he died.
Local police have previously said residents of Balad, a town about 18 miles north of Mogadishu, found the body of a man who might have been blown out of the plane by the blast.
An official told CBS News it was still unclear if this person was involved or not. In fact, authorities do not know for sure if the person who had the bomb in their possession knowingly carried it on or was unknowingly used by terrorists.
In a statement issued after a Cabinet meeting Thursday, Deputy Prime Minister Mohamed Omar Arteh said the government would tighten the airport's security to prevent security threats.
Officials said they still have not received any credible claim of responsibility. Somalia faces an insurgency from the Islamic extremist group al-Shabab, which has carried out deadly attacks in Somalia and neighboring countries.