Adam " DJ A.M." Goldstein's mother has added a wrongful death claim to the $20 million lawsuit her son filed against Learjet and others after he was seriously injured in a September 2008 plane crash, according to a People report.

The suit, filed against the plane manufacturer, the pilots' estates and others, now alleges the crash--in which four people were killed--ultimately lead to the fatal drug relapse and overdose that took Goldstein's life in August. Since his death, friends and associates reportedly have said Goldstein--a recovering drug addict--fell from his sobriety after he was prescribed anti-anxiety drugs and pain medication to deal with the trauma and pain suffered in the plane crash.

Learjet previously has denied any wrongdoing.

A trial is set for March 2.