On April 19, 1998, at 1809 eastern daylight time (edt), a Good Velocity, N234Q, operated by a commercial pilot, was destroyed when during cruise flight, the airplane's engine lost power. During the subsequent forced landing, the airplane struck some trees and impacted the terrain. Visual meteorological conditions prevailed at the time of the accident. The illegal smuggling flight was being conducted under 14 CFR Part 91. No flight plan was on file. The pilot was fatally injured. The origin of the illegal flight was unknown; however, the airplane crossed the United States-Mexico border near Big Bend National Park, Texas, at approximately 0830 edt. A U. S. Customs Service official said that at approximately 0830 central daylight time (cdt), the U. S. Customs Service Air Interdiction Coordination center (DAICC), at Riverside, California, received notification from a park ranger at Big Bend National Park, Texas, of an unidentified airplane entering the United States from Mexico. This airplane did not notify U. S. authorities of its arrival. At 0840 cdt, a U. S. Customs Service aircraft was dispatched from its home base and intercepted the airplane near Alpine, Texas. U. S. Customs Service aircraft followed the airplane on a northeasterly heading for over 8 hours, until arriving in the Detroit, Michigan area. The flight covered a distance of more than 1,200 miles. The airplane was observed overflying the Detroit Metropolitan Airport and circling over the downtown area, until it descended and crashed into an athletic field. A Federal Aviation Administration (FAA) inspector examined the wreckage at the accident site. The accident site was located in a park area approximately 10 miles northeast of the Detroit Metropolitan Airport. Trees on the south-southeast side of the park showed shear impact damage to trunks and branches approximately 50 feet up from their bases. The airplane was found resting inverted in a nearby baseball field, oriented on a 360 degree heading. The airplane's forward fuselage and cockpit area were crushed down and inward. The windscreen was broken out. The wings were broken downward and aft. Both vertical stabilizers and rudders were broken aft. The airplane's engine was broken off and found resting 200 feet north of the airplane. Examination of the airplane's engine and fuel system revealed that the airplane was void of fuel. Flight control continuity was confirmed. Examination of the airplane's other systems revealed no anomalies. Approximately 408 pounds of marijuana were recovered from the wreckage. The results of FAA toxicology testing of specimens from the pilot revealed the following volatile concentrations: 44 micrograms per milliliter(ug/ml, ug/g) of Acetaminophen was detected in urine. 30 (ug/ml, ug/g) Salicylate was detected in urine. The Director of Quality Control for the FAA Toxicology and Accident Research Laboratory stated that acetaminophen is taken for reducing fever or headaches. Volatile concentrations of 10 to 20 (ug/ml, ug/g) of acetaminophen detected in body fluids is considered normal. Toxicity occurs at 150 (ug/ml, ug/g). Acetaminophen can be purchased over-the-counter without a doctor's prescription. Salicylate is a by-product of aspirin. When aspirin breaks down in the body, salicylate is produced. Volatile concentrations of 30 (ug/ml, ug/g) of salicylate detected in body fluids is considered normal. Medications which break down into salicylate can also be purchased over-the-counter without a prescription.