Ruiz did not offer any explanation for what may have caused the plane to plummet.
Ruiz said the pilot, Miguel Perez Soto, had a valid Mexican pilot's license that would have expired in January. Photos of a temporary pilot's certificate issued by the U.S. Federal Aviation Administration found amid the wreckage said that Perez was 78 years old. The transportation department said Wednesday that he was flying on a U.S. pilot's license that had no limitations preventing him from flying from the northern Mexican city of Monterrey to the central city of Toluca early Sunday morning.
Ruiz said there is no age limit for flying a civil aviation aircraft, though for commercial flights it's 65. A pilot as old as 78 would be unusual in the United States.
The 43-year-old California-born Rivera known as the "Diva de la Banda" died while her career was peaking. She was perhaps the most successful female singer in grupero, a male-dominated Mexico regional style, and had branched out into acting and reality television.