NORTHERN MEXICO (CNN) -- Music star Jenni Rivera's remains have been identified and turned over to her family, a government spokesman in Mexico said Thursday.
Rivera was killed Sunday when the plane she was aboard plummeted from 28,000 feet, Mexico's transportation secretary said. The private jet crashed in a mountainous area 9,000 feet above sea level.
The remains of Rivera's publicist and the plane's co-pilot have also been identified, said Jorge Domene, a spokesman for Mexico's Nuevo Leon state.
The medical examiner's office in Monterrey compared DNA samples from the remains to a swab taken from the singer's brother Lupillo.
The cause of the crash is under investigation, in a probe that could last a full year.
Two lawsuits against the company that owns the jet accuse the firm of lying about its links to a businessman convicted of falsifying maintenance records.
Rivera had left a letter for her loved ones and gave instructions to her sister Rosie regarding the circumstances under which it should be read, her brother Pedro Jr. told CNN en Español on Wednesday.
He said the letter stipulated that she did not want to be cremated, as the family had originally planned to do, and that the authorities should hand over her remains to her siblings.
"Jenni always had advisers who helped her to work and to make things right," he said. "She prepared a letter about a month, month and a half ago."
He added that funeral plans had not been finalized but that a memorial would probably be held in Mexico.
The accident report will not be ready for nine months to a year, the secretary of communications and transportation said. Rivera, who was 43, is mourned by millions of fans.
Rivera and six others were thought to be aboard the plane, which lost contact with air traffic controllers soon after takeoff.
Known as "La Diva de la Banda" or the Diva of Banda Music, Rivera was a musical powerhouse with her Spanish-language performances of regional Mexican corridos, or ballads. For fans, the nickname captured her powerful voice and personal strength.
In recent years, she had been working to crack the English-language U.S. market and was reportedly on the verge of a crossover with a sitcom inspired by the success of "I Love Jenni," a Spanish-language reality TV show on Telemundo's mun2 network.
Rivera sold 15 million records, according to Billboard, and had recently won two Billboard Music Awards, including favorite Mexican music female artist.
In October, People en Español added her to its list of the 25 most powerful women.