Embattled rapper Chief Keef has begun a 20-day stint behind bars after failing a drug test.

The rising hip-hop star, real name Keith Cozart, turned himself in to police in Illinois on Tuesday (15Oct13) after testing positive for marijuana while on probation for a speeding charge dating back to May (13).

He was sentenced to spend the next 20 days in jail, but sources tell Tmz.com that Keef could walk free as soon as Wednesday (16Oct13) due to overcrowding issues.

The 18 year old, who is already on probation for a 2011 firearms conviction, is no stranger to the law - last month (Sep13), the landlord of his Illinois home asked a judge to evict the rapper from the $1 million (£667,000), six-bedroom property after he allegedly racked up debts of $10,000 (£6,670) in unpaid rent, while he has also been accused of failing to pay child support.

An arrest warrant was issued in September (13) after Keef failed to show for a court hearing over the matter.