SHARM EL-SHEIKH, Egypt -- CBS News correspondent Allen Pizzey says the focus of the investigation into the Russian plane crash in Egypt is now on airport staff and others who may have had access to the plane.
Egyptian security officers are reportedly even questioning hotel workers in the Red Sea resort town of Sharm el-Sheikh, paying particular attention to those involved in catering. Even in the capital city Cairo, international teams were inspecting baggage and cargo handling, and passenger screening operations at the main airport Tuesday, the Egyptian government said.
The head of Cairo's airport said caterers and security personnel were being asked questions by the teams, which came from Europe, Russia and Arab nations.
The Metrojet airliner, carrying 224 people, took off from Sharm el-Sheikh's airport but about 20 minutes into the flight something caused the Airbus A321 to break up and crash down into the Sinai Peninsula.
No one may be willing to say definitively that the crash was an act of terrorism rather than a mechanical failure, but the search for clues has taken on all the hallmarks of a crime investigation.
The key to figuring out what happened to the plane lies in forensic evidence, and the Russians and Egyptians have control of that.
But there is enough other evidence to have convinced U.S. and British officials to go with the bomb theory.
"Our conclusions and the decisions we have been taking are based on all the information available to us, some open source and some intelligence information," British Foreign Secretary Philip Hammond said.
Prompted in part by the hammer blow the plane crash has dealt the vital tourism industry, the Egyptians smell a conspiracy.
The front page of the state-owned Al-Gomhuria newspaper splashed the headline Tuesday: "The people defy the conspiracy -- Egypt will not cave in to pressures."
The Sinai-based ISIS affiliate that claimed credit for downing the plane has released videos purportedly showing the aftermath of Egyptian airstrikes in areas they control, to portray the government as the bad guys.
ISIS in Sinai, known as Ansar Beit al-Maqdis until it pledged allegiance to ISIS in late 2014, still operates with seeming impunity in a small but important part of the desert peninsula -- in spite of Egyptian government claims to have control.
The Sinai Peninsula "is well-known for illicit smuggling and ISIL Sinai has been able to acquire and use a range of weapons," a U.S. counterterrorism official told CBS News.