U.S. investigators suspect Malaysian Airlines Flight 370 continued flying for about four additional hours after it lost contact with air traffic controllers with its radar detection transponders intentionally turned off, suggesting the possibility that the flight may have been diverted to an undisclosed location, the Wall Street Journal reported Thursday quoting two people familiar with the investigation.

Meanwhile, Malaysia’s civil aviation chief said that planes sent on Thursday to check the location where Chinese satellite images showed signs of possible debris found nothing.

“There is nothing. We went there, there is nothing,” Azharuddin Abdul Rahman told reporters in Kuala Lumpur.

In this March 9, 2014 satellite image seen on the website of the Chinese State Administration of Science, Technology and Industry for National Defense, floating objects are seen at sea next to the red arrow which was added by the source. China's Xinhua News Agency reported Wednesday that the images show suspected debris from the missing Malaysia Airlines jetliner floating off the southern tip of Vietnam. (AP Photo/Chinese State Administration of Science, Technology and Industry for National Defense)

In this March 9, 2014 satellite image seen on the website of the Chinese State Administration of Science, Technology and Industry for National Defense, floating objects are seen at sea next to the red arrow which was added by the source. China’s Xinhua News Agency reported Wednesday that the images show suspected debris from the missing Malaysia Airlines jetliner floating off the southern tip of Vietnam. (AP Photo/Chinese State Administration of Science, Technology and Industry for National Defense)

According to the Wall Street Journal’s report, aviation investigators and national security officials now believe the aircraft may have traversed hundreds of additional miles based on data from its engines that are automatically transmitted to the ground as part of a routine maintenance program.

“U.S. counterterrorism officials are pursuing the possibility that a pilot or someone else on board the plane may have diverted it toward an undisclosed location after intentionally turning off the jetliner’s transponders to avoid radar detection, according to one person tracking the probe,” the Wall Street Journal wrote.

That theory has raised even more complex questions, such as why might the aircraft have been commandeered. “Some of those theories have been laid out to national security officials and senior personnel from various U.S. agencies, according to one person familiar with the matter,” the Journal wrote.

One unnamed source told the Journal that at one briefing, officials were told that investigators are actively pursuing the idea that the plane was diverted “with the intention of using it later for another purpose.”

Vietnamese Air Force Col. Pham Minh Tuan uses binoculars on board a flying aircraft during a mission to search for the missing Malaysia Airlines flight MH370 in the Gulf of Thailand over the location where Chinese satellite images showed possible debris from the missing Malaysian jetliner, Thursday, March 13, 2014. (AP Photo)

Vietnamese Air Force Col. Pham Minh Tuan uses binoculars on board a flying aircraft during a mission to search for the missing Malaysia Airlines flight MH370 in the Gulf of Thailand over the location where Chinese satellite images showed possible debris from the missing Malaysian jetliner, Thursday, March 13, 2014. (AP Photo)

Six days into the search, there was still no concrete evidence as to whether the plane had flown elsewhere, as in the theory put forward in the Wall Street Journal report, or if it had crashed, perhaps hundreds of miles from where search efforts have been targeted to now.

The Wall Street Journal reported that it had confirmed that the pilot had the ability to manually turn off the transponder, but that a mid-air catastrophe could also have destroyed it.

It also noted that Malaysian police visited the home of at least one of the two pilots according to local media outlets.

Neither Malaysia Airlines nor Boeing offered reaction to the Journal’s report, but Reuters quoted a senior Malaysia Airlines executive on Wednesday saying that the airline had “no reason to believe” that any actions by the crew caused the disappearance of its jet.

Rolls-Royce is the manufacturer of the aircraft’s engines’ onboard monitoring system which periodically transmits live data about aircraft movements, including altitude and speed, in 30-minute increments to ground facilities. The company also did not provide a comment to the Journal directly addressing its report about the potential significance of the transmitted data.

“A total flight time of five hours after departing Kuala Lumpur means the Boeing 777 could have continued for an additional distance of about 2,200 nautical miles, reaching points as far as the Indian Ocean, the border of Pakistan or even the Arabian Sea, based on the jet’s cruising speed,” the Journal wrote.

Flight MH370 was last seen on air traffic controllers’ screens less than one hour after takeoff.

Images captured by a Chinese satellite Sunday and released Wednesday afternoon showing three sizable floating objects off the southern tip of Vietnam had raised the possibility of debris from the missing Malaysia Airlines jet.

According to the Associated Press, dozens of ships and aircraft from 12 nations are contributing to the search effort in the Gulf of Thailand and the Strait of Malacca spanning 35,800 square miles which it compared to an area the size of Portugal.

“If the Wall Street Journal report is confirmed, the search area will have to significantly expand.
Authorities have not ruled out any possible cause, including mechanical failure, pilot error, sabotage and terrorism, and they are waiting to find any wreckage or debris to determine what went wrong,” the AP noted.

After six days of intense searches and the raising of multiple theories, the mystery over what happened to the plane and its 239 passengers continues.