The Mexican registered aircraft collided with hilly terrain while maneuvering for a presumed landing following fuel exhaustion in a remote desert area near the Mexico and US border. Post crash examination of the fuel system revealed that it was intact and only about five ounces of fuel were found in the total system. The fuel system had been modified with the addition of non standard long range bladder tanks in the wings. According to information from the County Sheriff's Office, US Customs and the Drug Enforcement Administration, the aircraft reportedly departed Durango, Mexico, at an unknown time with a presumed destination of Nogales, Mexico (17 miles south of the crash site). US Customs and DEA reported that the aircraft entered the United States at low altitude without a flight plan or entry declaration. The aircraft was observed by ground witnesses flying low in the gullies and valleys of the hilly desert terrain, then they heard the engine sputter and stop. The aircraft collided with the slope of a hill side in a gully with flaps in a landing configuration.