Aircraft expert Mark Schmaltz speaks next to a photo of the type of aircraft involved as attorneys announce a lawsuit on behalf of four associates of
Aircraft expert Mark Schmaltz speaks next to a photo of the type of aircraft involved as attorneys announce a lawsuit on behalf of four associates of Mexican singer Jenni Rivera, who perished along with her in a plane crash in Mexico in December, at a news conference in Los Angeles Thursday, Jan. 10, 2013. (AP Photo/Reed Saxon)

Families of four members of Jenni Rivera's entourage who were killed when the singer's plane crashed last month in Mexico have filed a lawsuit against the jet's owners and Rivera's Encino-based company.

The lawsuit claims the pilots flying the LearJet were not licensed to operate the plane and that the jet was poorly maintained.

The lawsuit was filed in Los Angeles Superior Court Thursday on behalf of four members of Ramirez's entourage, all of whom died in the Dec. 9 crash: Arturo Rivera, her public relations aide; Jorge Vasquez, her hairstylist, Jacobo Yebale, her makeup artist; and her attorney Mario Pacheco.

The lawsuit seeks punitive damages against the owner and previous owner of the plane, and Rivera Enterprises.

Rivera Enterprises is named because it's believed the late singer's company may have played a role in chartering the plane, said Paul Kissel, attorney for the four families, at a press conference in downtown Los Angeles.

The lawsuit claims the 1969-vintage Learjet LJ25, which is owned by Starwood Management LLC, was previously damaged in a 2005 incident.

Additionally, neither of the two pilots, Miguel Perez Soto, 78, and Alejandro Torres, 20, were sufficiently trained or licensed to fly the plane.

Vasquez, Yebale, Pacheco, Arturo Rivera and Jenni Rivera died last month when the jet crashed in northern Mexico about 15 minutes after departing Monterrey, Mexico.

The two-engine turbojet plunged almost vertically from more than 28,000 feet and hit the ground in a nose-dive at a speed that may have exceeded 600 miles per hour, Mexican transportation officials said.

The crash is being investigated by the both Mexican authorities and the National Transportation Safety Board.

Rivera was known in Mexico and the United States as "La Diva de la Banda," a singer who had sold more than 15 million records of banda music. Born and raised in Long Beach, Rivera was one of the biggest stars of the Mexican regional style known as grupero music, which is influenced by the norteƱo, cumbia and ranchero styles.

The home of Rivera's mother in Lakewood, where numerous press conferences were held in the days following the plane crash, was quiet Thursday. No one answered the door and no cars were parked in the driveway, near the remains of a memorial of flowers, photos and other mementos set up by fans that appeared to be in the process of being cleaned up, with many items in a nearby trash can.

The family did not immediately respond to an email sent Thursday seeking comment about the lawsuit.

Staff Writer Phillip Zonkel contributed to this report.