Mexican-American singer Jenni Rivera was in the "final stages" of purchasing the plane she eventually died in early Sunday morning, according to a Los Angeles Times exclusive interview on Wednesday.

"La Diva de la Banda" was on her last trial flight before she bought the plane.

In an interview with The Times, Christian E. Esquino Nuñez, an executive of Starwood Management, which owned the doomed Learjet 25, said Rivera was preparing to buy the plane for $250,000 and as a result the company let her "demo" the aircraft for free the night of the crash.

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Esquino Nuñez , 50, also said maintenance and safety issues "had nothing to do with the accident," and instead questioned the pilots in command. In fact, the self-described operations manager for Starwood Management hypothesized that the 78-yr-old pilot, Miguel Perez Soto, may have had a heart attack which led to the aircraft in the hands of an unexperienced or "green" pilot identified as Alejandro Torres.

The 1969 Learjet 25 underwent a top-to-bottom inspection this summer, Esquino Nuñez told The Times.

Esquino Nuñez acknowledges his criminal history. He was indicted in 1993 for drug smuggling in Florida and convicted in 2005 on charges of creating fraudulent logbooks for six air crafts that he later sold to buyers in the United States.

Secretary of Communications and Transportation Gerardo Ruiz Esparza emphasized Tuesday that the pilots who flew the Learjet 25, Perez Soto and Torres, had valid licenses in accord with Mexican law.

Jenni Rivera's Plane Nose-Dived From 28,000 Feet, Officials Say

Details of the crash continued to emerge Wednesday following the first detailed account of the moments leading up to the crash that killed Rivera and six other people.

Ruiz Esparza told Radio Formula that the twin-engine turbojet hit the ground 1.2 miles from where it began falling. Then the plane nose-dived almost vertically from more than 28,000 feet at a speed that may have exceeded 600 miles per hour.

These aircraft require an awful lot of skill to fly and don't leave a lot of margin for error.

- Lee Collins, a cargo airline pilot and executive vice president of the Coalition of Airline Pilot Associations in Washington

"The plane practically nose-dived," he said. "The impact must have been terrible."

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Ruiz did not offer any explanation of what may have caused the plane to plummet, saying only that "The plane fell from an altitude of 28,000 feet ... It may have hit a speed higher than 1,000 kph (621 mph)."

Ruiz said 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 and found amid the wreckage said that Perez was 78.

Ruiz said there is no age limit for flying a civil aviation aircraft, though for commercial flights it's 65. In the United States it's unusual for a pilot to be 78.

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The extremely high speeds at which Learjets can fly are close to the speed of sound and make them especially challenging to fly, pilots and safety experts said.

"These aircraft require an awful lot of skill to fly and don't leave a lot of margin for error," said Lee Collins, a cargo airline pilot and executive vice president of the Coalition of Airline Pilot Associations in Washington.

He said that in situations in which a pilot loses control of an aircraft, the plane could "get into a high-speed dive and inadvertently go through the speed of sound." Collins said.

A 30-year study of private jets from 1964 to 2004 from Robert E. Beiling and Associates obtained by Fox News Latino underscores its difficulty. The rate of accidents for the 629 Learjet 24's and 25's active during the time was 24.2 percent. In comparison, the Ce500 had an accident rate of 10.1 percent.  

"The Learjet 24/25 series has been 2.34 times more likely to be in an accident when compared with other light jets built in a similar era," said Kevin O'Leary, President of Jet Advisors, a Private Jet Advisory Firm.

One possible cause for a nose dive like the one described by Mexican officials would be a drastic failure of the flight controls, the ailerons, elevators and stabilizers, said former NTSB board member John Goglia, an aviation safety expert.

Jenni Rivera: Plane or Pilot to Blame?

"High performance airplanes by their nature have issues," Goglia said. "The airplane flies faster than the human mind (can keep up) sometimes. ... It takes a lot of skill to stay in front of that airplane."

Mexican authorities were performing DNA tests Tuesday on remains believed to belong to Rivera and the others killed when her plane went down.

Investigators said it would take days to piece together the wreckage of the plane carrying Rivera and find out why it went down. In fact, they said, the investigation could take nine months to a year to fully complete.

The NTSB sent a team to help investigate the crash of the Learjet 25, which disintegrated on impact in the rugged terrain in Nuevo Leon state in northern Mexico.

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