SANFORD, Fla. -- The landing gear and flaps of a twin-engine plane that crashed into a Sanford neighborhood were not deployed, suggesting the pilot was not prepared to land, a federal official said Thursday.

---

INVESTIGATION IMAGES: NTSB At Crash Scene
VIDEO: New Details Released By NTSB Investigators
THE VICTIMS: Images Of All Victims In Crash

---

Still, investigators have not found any clear signs to explain exactly why the Cessna 310 dove into the residential area Tuesday, killing five people and destroying two homes, said Robert Sumwalt, vice chairman of the National Transportation and Safety Board.

Crews from the agency wrapped up their on-scene collection of evidence on Thursday.

Sumwalt said it is still unclear who was piloting the plane: Dr. Bruce Kennedy, a Daytona Beach plastic surgeon and husband of a prominent NASCAR official, or Michael Klemm, a NASCAR aviation pilot. NASCAR has said Kennedy was at the controls.

The plane's cockpit started to fill with smoke as it approached Orlando-Sanford International Airport. It crashed in a subdivision about 3 miles from the airport.

During Thursday morning's news conference, investigators released a more clear timeline of the events that led up to the crash, specifically that the call about smoke in the cockpit came just two minutes before the Cessna dropped off radar. Investigators also said that, for whatever reason, the plane was not ready to land, nor was it flying in a landing pattern of any kind, possibly falling out of control toward the ground.

"From examination of the wreckage yesterday, it does not appear that the airplane was in a configuration that would be associated with landing an airplane. For example, the gears appeared to have been retracted, as well as the flaps. So it does not appear the plane was in a landing configuration at the time of impact," Sumwalt explained.

Both men died in the crash. Also killed were law student Janise Joseph-Woodard, her 6-month-old son and their neighbor, 4-year-old Gabriela DeChat, after their houses were engulfed by flames from the crash. DeChat's parents and brother were badly burned.

Investigators were to return to Washington, where they will immediately begin sifting through the evidence, Sumwalt said. The investigation could take up to a year to complete.