My refund is scheduled to be returned by the 16th and today is the 13th. When I track my refund it states "Your tax return is still being processed"

Where did you get the 16th date? The only place you can get a firm date is the IRS tracking web site.

Expected Delivery Date... February 16

That is purely an estimate provided by TurboTax based on historical refund payment times. It is nothing more than a broad estimate.

I understand that. My question is, when I track my refund, it states "still processing." I was curious as to what that means. It went from accepted back to processing. Does this mean it is being reviewed manually?

It's not possible to know exactly what is happening with your return. You would have to contact the IRS to find out.

The IRS told me that my return has been flagged as part of a scam that they are investigating.  According to them, it will take another eight weeks before they get back to me about their findings!!!!!