Federal investigators have found preliminary evidence that a Learjet 60 may have begun breaking apart before crashing in Palm Beach County, Florida, on Nov. 1, killing all nine people aboard.

During a Nov. 2 briefing, National Transportation Safety Board member Tom Chapman said investigators had identified indications of an in-flight breakup, although they have not determined which aircraft components may have separated or what caused the crash.

The aircraft, operated by Aurora Aviation under the name Upper Jets, was flying from Austin, Texas, to the Bahamas when the crew reported icing, moderate turbulence and precipitation at 35,000 feet. Shortly after requesting clearance to climb to 37,000 feet, the aircraft entered a rapid descent.

Chapman said weather conditions are a major focus of the investigation. Investigators are also examining the aircraft's maintenance history and working to determine whether a cockpit voice recorder was installed at the time of the accident.

Recovery crews face challenges accessing the main wreckage, which is embedded in a crater partially filled with water. Investigators are examining debris scattered across nearby residential and commercial properties and may expand their search beyond the immediate crash site.

The NTSB emphasized that the investigation remains in its early stages and no probable cause has been determined.