Investigators sifting through the remains of a Russian jet that crashed in the Sinai last week have uncovered intelligence about a “two hour timer,” and are connecting it with their working theory that an ISIS affiliate in the region planted a bomb on the plane’s fuel lines before it left the popular Sharm el-Sheikh resort area for St. Petersburg.

A source told Fox News about the discovery of the timer, but wasn’t clear whether or not investigators found physical evidence, or were able to decipher communications between terrorist operatives. This new information supports the involvement of an “airport insider,” and investigators are now interviewing ground crews and baggage handlers who had access to the plane before it left Egypt.

More from Fox News:

“If proven accurate, if ISIS did put a bomb on this aircraft which I believe to be true, it’s a new chapter with respect to ISIS,” Texas Republican Rep. Mike McCaul told Fox News. McCaul — who receives regular briefings — cannot discuss classified information, but said the Obama administration has consistently underestimated ISIS by emphasizing its focus on gaining territory, rather than expanding its reach to global plots.

“We always assumed Al Qaeda had this capability but now if ISIS has this capability, the threat to American airlines as well and our homeland, I think is very significant.”

Fox News was told that Metrojet 9268 disintegrated approximately 23 minutes into the flight, and investigators are now focused on a “90-minute window” before the flight took off and who had access.

Right now, investigators’ theories about an ISIS bomb plot are bolstered by three main “data points”:

1. The new “two-hour timer” intelligence
2. The fact that the plane was in the air for just 23 minutes before it went down (which lends credence to the theory of an insider)
3. The fact that an ISIS affiliate claimed responsibility

Context also matters. The airport servicing Sharm el-Sheikh is notoriously lax in its security procedures. An insider makes sense here because 1) he or she would have had access to the plane, and 2) would most likely know enough about plane mechanics to strategically place the bomb so as to maximize damage and minimize any chemical signatures. Investigators were unable to immediately find any tell-tale residue near the crash site, which may point to a bomb placed near the plane’s fuel lines: bomb goes off, fuel spills, burns, and destroys trace explosives.

Egyptian officials have downplayed the possibility that this was an act of terror, but the evidence seems to be stacking higher and higher against that line of thinking.

We’ll keep you updated as the story progresses.

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