Crews searching farm fields near Eagle Lake, TX found an airplane part yesterday that came off a Continental Express commuter flight last week before a crash that killed all 14 people aboard. The part, a 9-foot de-icing attachment, is considered a vital clue in the investigation into what caused Flight 2574 to crash Wednesday, en route from Laredo to Houston. Three crew members and 11 passengers died. Investigators speculated Saturday the de-icing boot fell off because 43 screws were missing from the leading edge of the plane's stabilizer, where the de-icer would have been attached. The sudden loss of the de-icer would stall the tail and cause the plane to nose dive, Kolstad said at a press briefing on the crash. It was found about three-quarters of a mile northeast of the crash site. *PASSAGE END INSTRUCTIONS: Schematize the reasoning of the investigators, locating exactly four pieces of support, and taking the conclusion to be "The plane's de-icing boot fell off mid-flight." (There are no tributaries.)