The owners of a Learjet private plane that crashed in December (12) killing Mexican singer Jenni Rivera are challenging a wrongful death lawsuit filed by four families who lost their loved ones in the tragedy.

The Dejame Volver Contigo hitmaker passed away on 9 December (12) after the plane went down in Mexico, killing two pilots and five passengers.

In January (13), the families of Rivera's publicist Arturo Rivera, make up artist Jacobo Yebale, hairstylist Jorge Armando Sanchez Vasquez and attorney Mario MACias Pacheco filed a lawsuit against Starwood, Rodatz Financial Group McOco, Inc. asking a Los Angeles court to determine damages. Jenni Rivera Enterprises, which booked the plane is also listed as a defendant.

Representatives from McOco, Inc. claim they are not subject to jurisdiction in California, because the crash was in Mexico and they have requested the lawsuit is thrown out or set aside.

Attorney Paul Kiesel tells, "Defendants are challenging the lawsuit on procedural grounds rather than dealing with the tragic loss of life that resulted from the crash of their poorly maintained and improperly operated 43-year old Learjet."

A separate lawsuit filed in March (13), on behalf of Isabel Carrero Gomez, the widow of the plane's pilot is also being challenged. The lawsuits have been consolidated and will be considered by the same judge.

A court date has been set for 6 September (13).