NEW YORK CITY: A passenger jet en route to Madrid from Atlanta was forced to land at New York's Kennedy Airport after a passenger discovered an "alarming" message on the bathroom wall. Federal Bureau of Investigation officials would not elaborate on the message found on Delta Airlines flight 108, but it is believed to have warned of a bomb onboard. The FBI said it will hold the plane until all 170 passengers are questioned, leading to speculation the agency suspects one of them is responsible. "We are going to check everything," said a Port Authority spokesman. "You just can't take any chances these days." The investigation is expected to last most of the morning. The scare is the second this week at JFK. Yesterday, a Pan Am airliner was found with several cockpit wires cut in half. A report in The New York Times says the damage may have been caused by a worker angry the airline was not using union mechanics. The jet was scheduled to takeoff for Miami within hours of the discovery, but officials said the plane was never in danger.