Chicago rapper Chief Keef (17) is currently serving a 60 day sentence in a juvenile corrections facility for violating his probation on a gun charge, now he's allegedly being sued for child support by a middle schooler he may have impregnated back in 2011.

According to TMZ.com, the girl filed a petition for child support in a Chicago claiming that Kieth Cozart (Chief Keef) fathered a daughter with her in 2011.

In Illinois, it is considered a misdemeanor for two people under the age of 17 to have sex ... even if they're in a consensual relationship. When both parties are between 9 and 17 years old, the older person commits a crime called "criminal sexual abuse."

Punishment for the crime includes a max sentence of one year in jail ... and a requirement to register as a sex offender for ten years -- but in reality, these cases are almost never prosecuted.

The only way the rapper would be charged is if the girls parents file charges. Keef is being sued for child support, as well as health insurance and medical expenses.

Check out Chief Keef's latest video for 'Love Sosa".