Rob Kardashian Knew of Lamar Odom Drug Scandal?

Rob Kardashian knew that his brother-in-law, Lamar Odom, was abusing drugs for more than a year, Radar Online reported Friday.

Rob has lived with Khloe and Odom on and off for the past three years. A source said that Rob saw first hand the secret Khloe has been keeping from the rest of the family and public.

"[He has] known about Lamar's drug addiction for over a year. How could he not as he has lived under the same roof with Lamar and Khloe? Rob even spent a significant amount of time with Khloe and Lamar when he was traded to the Dallas Mavericks," a family source said.

Since the fallout of Khloe's marriage, Rob has not left her side. Sources said that the only Kardahashian son has stepped up in the role of his sister's protector. Although he was once close to Odom, his loyalties are reserved only for Khloe.  

"Rob isn't a party animal like Lamar, and drugs just aren't his scene. The two used to be very close, but have drifted apart because Lamar has been abusing Oxy and cheating on Khloe. Rob has continued to live at the Tarzana mansion to support Khloe, he really has her back."