Looks like this scandal's going DEEPER and investigators are now possibly implicating Lori Loughlin's 19-year-old daughter Bella Giannulli in the college admissions scandal!

Giannulli was served a letter from federal prosecutors in Massachusetts earlier this month in the Operation Varsity Blues investigation informing the then-USC student she was the subject of the investigation and that criminal charges could be brought against her.

After her parents pleaded not guilty earlier this month, after rejecting a plea deal, Isabella deleted her Instagram account (so you KNOW it's serious!).

So far, no students have been charged in the investigation but court docs prove some kids knew what their parents were doing on their behalf by funneling money through their college admissions counselor's fake charity fund to weasel their way into school.

Giannulli isn't the only student related to the scandal to receive one of these letters, however her sister Olivia Jade, 20, did not. Apparently all five students who are being investigated are children of parents who rejected plea bargains.

Watch the above video for ever MORE dirt on this scandal!