Chief Keef is back behind bars for probation violation.
TMZ.com says the teen rapper turned himself into authorities in his native Chicago Tuesday after testing positive for marijuana.
He was sentenced to 20 days in jail but may not serve all of his time due to jail overcrowding.
Chief Keef, whose real name is Keith Cozart, was ordered to undergo random drug testing as part of his probation for a speeding ticket and prior misdemeanors back in May.
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