The FBI has joined in the investigation into the sudden and mysterious disappearance of Wall Street Journal reporter David Bird.

Bird, 55, was last seen leaving his home in northern New Jersey on Jan. 11. He reportedly left the house without his cell phone or the medication that he needs daily following a liver transplant.

Bird told his family he was going for a walk from their Long Hill Township home, but never returned. Expansive searches of the area - including swamps and portions of the Passaic River - have yielded no clues.

Bird is a reporter for the Wall Street Journal, covering OPEC, a collection of oil-rich countries. He also worked for Dow Jones & Co., the newspaper's publisher, for more than 20 years.

One report indicated that Bird's credit card had been used in Mexico, but police have not confirmed that.

Bill Hemmer discussed the case this morning with Fox News contributor and former LAPD homicide detective Mark Fuhrman.

He emphasized that Bird's need for a medication that is not easy to obtain would seem to rule out the possibility that he left voluntarily.

"He would have to have another source (for the medication) if he voluntarily disappeared. He would have to have a method of transportation, he would have to have identification, a passport to get into Mexico if he actually did," said Fuhrman, adding that usually when the FBI gets involved it means there is a strong suspicion of foul play.

Bird is 6-foot-1, about 200 pounds and was last seen wearing a bright red jacket with two yellow zippers. Anyone with information should call 908-647-1800 or 911.

Watch the segment above.