Katherine Jackson '4 Years Is Not Enough'

11/29/2011 11:00 AM PST

Katherine Jackson: '4 Years Is Not Enough'

Katherine Jackson wants Conrad Murray to rot behind bars -- telling reporters outside the courthouse, the doctor's 4-year sentence is "not enough."

Speaking to KTLA ... Katherine added, "Four years won't bring my son back" -- but she admits ... Judge Michael Pastor was extremely fair with his sentencing.