KUALA LUMPUR, Malaysia – A search for a missing Malaysian airliner with 239 people on board is getting a potential boost from a satellite communications company, which announced Friday that it had registered signals from the plane after it took off from the Malaysian capital six days ago.

With the mystery of the plane’s disappearance continuing to baffle search teams, investigators and aviation experts, inquiries are focusing on the prospect of foul play.

“The facts are all over the place,” a U.S. official told The Washington Post. “It’s looking less and less like an accident. It’s looking more like a criminal event.” The official asked not to be identified because he is not authorized to speak publicly.

Reuters news agency reported Friday that investigators now suspect the flight was following a commonly used route between navigational waypoints when it was last spotted by military radar off Malaysia’s northwestern coast early Saturday – a course heading toward India over the Andaman Sea and the Bay of Bengal that indicated the plane was being flown by someone with aviation training.

“What we can say is we are looking at sabotage, with hijack still on the cards,” the agency quoted an unidentified senior Malaysian police official as saying.

Inmarsat, a British company that provides global mobile satellite telecommunications services, said in a statement Friday: “Routine, automated signals were registered on the Inmarsat network from Malaysia Airlines flight MH370 during its flight from Kuala Lumpur.” It said the information was provided to its partner, SITA, a European information technology company that serves the air transport industry, and that SITA “in turn has shared it with Malaysia Airlines.”

The cryptic announcement did not provide any clues on where the missing Boeing 777 might have gone or how long it might have flown. But The New York Times quoted an Inmarsat vice president, David Coiley, as saying the company had recorded electronic “keep alive” ping signals that could be analyzed to help estimate the plane’s location.

Word of the signal transmissions came as the search was rapidly expanding from the relatively shallow waters around Malaysia into the much deeper Indian Ocean, based on signs that the plane flew westward well after disappearing from civilian radar early Saturday.

Malaysian authorities said Friday that the search has no clear leads, but they said U.S. investigators were trying to determine the plane’s whereabouts from potential communication with a satellite.

Senior U.S. officials said earlier that an onboard communication system sent signals for at least four hours after Malaysia Airlines Flight MH370 lost other forms of contact, an indication that the jet might have stayed in the air for that time.

If the plane followed a westward course after losing contact, it could have traveled toward India, the latest country to take a major role in the multi-nation search. A senior Indian official said Friday that a search team is focusing its efforts in the waters west of Malaysia based on coordinates provided by the Malaysian government. But he said he was not sure what data the Malaysians had that led them to target those areas.

Military radar-tracking evidence suggests that the plane was deliberately flown across the Malay Peninsula toward India’s Andaman Islands, a sliver of isles south of Myanmar, also known as Burma, and hundreds of miles east of the Indian mainland, Reuters news agency reported Friday.

The fate of the plane remains unknown after it vanished less than an hour into its flight from Kuala Lumpur to Beijing. But aviation experts and U.S. officials increasingly suspect that the disappearance involved either sabotage or hijacking by crew members or a passenger with aviation training.

Malaysia’s acting transport minister, Hishammuddin Hussein, said an investigation into the passengers and pilots was “ongoing,” although the pilots’ homes had not yet been searched.

Officials in Port Blair, the capital of India’s Andaman and Nicobar Islands, said they have told local fishermen and authorities to report any unusual finds. India’s role, though, goes well beyond the islands. Captain D.K. Sharma, an Indian navy spokesman, said Malaysia has given India a massive search grid – some 13,500 square miles, an area about the size of Maryland.

The red-eye flight to Beijing lost contact early Saturday over the Gulf of Thailand – northeast of the Malay Peninsula. But a growing number of indicators, including a Malaysian military radar reading of an unidentified aircraft, suggest the plane might have veered west after cutting its transponders.

The search for the aircraft now involves 13 countries and more than 100 ships and aircraft. Hishammuddin emphasized Friday that the search was expanding not because of any particular leads, but because the initial, more targeted search had turned up no evidence or debris.

“A normal investigation becomes narrower with time,” Hishammuddin said. “But this is not a normal investigation. We are looking farther and farther afield.”

In a signal that U.S. officials believe the plane likely veered west, the Navy said Friday that one of its ships involved in the hunt, the destroyer USS Kidd, arrived in the northwestern section of the Strait of Malacca, on the western side of the Malay Peninsula, from the Gulf of Thailand to the northeast. A maritime surveillance aircraft, the P-8A Poseidon, is scheduled to arrive in the region Saturday, said Lt. David Levy, a Navy spokesman.

A Navy P-3C Orion surveillance aircraft already in the area completed a search Friday of the northwestern section of the Malacca Strait, “where it flew approximately 1,000 miles west with nothing significant to report,” Levy said.

One of the most important clues for investigators could come from messages sent by the plane and picked up by satellites. Though Malaysia Airlines says satellite-based communication stopped functioning some 40 minutes after takeoff, U.S. officials say some form of signaling continued for at least several additional hours, an indication that the plane remained in the air during that time.