The company that owns a luxury jet that crashed and killed Mexican pop superstar Jenni Rivera is under investigation by the U.S. Drug Enforcement Administration.It has had two planes seized by the agency this year.DEA spokeswoman Lisa Webb Johnson confirms the planes owned by Las Vegas-based Starwood Management were seized in Texas and Arizona. She declined to discuss details.The man widely believed to be behind the aviation company is an ex-convict named Christian Esquino who has a long and checkered legal past, including convictions for fraud, one as part of a sweeping drug investigation in Florida in the late 1980s.The 43-year-old California-born Rivera died when the plane she was traveling in nose-dived into the ground while flying in Mexico Sunday morning.