Washington, Sep 21 : The US Marines has launched an official probe into the sudden disappearance of one of its most prized $100 million F-35 stealth fighter jets Sunday over South Carolina eventually leading to its crash in Charleston in the same state. What made the pilot eject to safety is among various theories being probed. Was it shot down by somebody is also an angle being probed, media reports said. The F-35 jets' debris was located outside Charleston in South Carolina Monday and confirmed to be remains of the missing aircraft after what the US military initially suspects to be a 'mishap' or a ' malfunction' in which the jets pilot ejected from the craft. The F-35 jet fighter, spawning out of America's most expensive stealth fighters that duck the radar comes out of a massive funding of $1.7 trillion that took nearly 30 years to develop, can fly undetected for long on autopilot after a pilot ejects from the plane, ABC Network reported. The overall recovery process for the debris and the F-35B Lightning II has begun, a US marine corp official told ABC News in a pair of statements. The official did not detail the recovery process and its stages except to say the process is ongoing. It has not been publicly confirmed what led the pilot to eject or what brought the F-35 down. "It's very frustrating to not have any answers," Republican Nancy Mace, R-S.C., told the local affiliate WCICV. The US Marines estimate the likely cost of the lost jet, a sophisticated stealth plane, at around $100 million. A South Carolina law enforcement helicopter located the debris nearly 60 miles north of Charleston on Monday at 5 p.m. EDT. Local law enforcement and the Marine Corps Emergency Reclamation Team identified the missing jet and cordoned off the perimeter and secured the crash site from public view. The pilot, who ejected himself from the F-35, was discharged from the hospital on Monday afternoon. The pilot suffered no major injuries and was in stable condition before being discharged, an official said. No civilian injuries were reported from the crash site. The pilot ejected himself from the aircraft at an altitude of over 1,000 feet "and one mile north of the Charleston International Airport", according to the official. He landed safely in a residential backyard. The pilot had "experienced a malfunction and was forced to eject", the US marine official said. Officials said in a statement on Monday that "we are unable to provide additional details to preserve the integrity of the investigation". Mace, who has been critical of the Marines' handling of the incident so far, said Monday, "Not to be able to provide answers to the community, you know, when mistakes happen -- we should be able to take responsibility for it and communicate and be transparent with the public." "Even though it's a stealth aircraft, (that can beat the radar), losing it is hard to understand. ... seems ridiculous that an aircraft this expensive, this sophisticated, could just vanish from the skies ," he said. Usually , a transponder aboard the F-35 helps locate the plane in such situations but the Marine Corps hasn't confirmed if the device malfunctioned. "If there was, say, an electrical failure on board where the transponder, the beams out to the radar, was no longer functioning -- then it becomes a stealth aircraft, essentially invisible to radar," an official said. Jittery about the vanishing of the stealth jet fighter, the US marines issued a public appeal over the media asking American citizens for help in finding the missing aircraft inviting the wrath of the Republicans . They even posted a phone number to call the marines department with any information. /IANS