Federal investigator say they can't rule out anything that may have caused the fiery plane crash that killed five people and crashed in I-287 in New Jersey.

"We're looking at man and machine and environment and all those in great detail," said Ralph Hicks, the investigator in charge from the National Transportation Safety Board.

NTSB investigators spent the day scouring the wooded area and removing the biggest parts of the 6-year-old single engine, turbo prop plane from the median of the interstate.

Investigators are analyzing the conversation between a calm and seemingly confident pilot, Jeffrey Buckalew and the tower. Controllers warned of a potentially hazardous freezing water vapor called rime in the area where the socata was flying:

Controller:  "There are reports of moderate rime. If it gets worse let me know and when center takes your handoff, I'll climb you and maybe get you higher."

Buckalew:  One Charlie Alpha, we'll let you know what happens when we get in there and if we can go straight through it then no problem for us."

Investigators still don't know if the icing boots on the two-point-seven million dollar plane were ever activated:

"The aircraft was equipped with a de-ice system that is engine activated. We don't know if the ice came off the aircraft," Hicks said.

The Buckalew family had just sent out a Christmas card, showing a smiling first grader, Meriweather, and fifth grader Jackson and the family dog, all killed along with mother, Corinne, father and pilot Jeff and his investment bank partner Rakesh Chawla.

The Virginia school that the Buckalew children attended put out instructions on their website to help families who knew them cope with this tragedy so close to Christmas.