Battery Drain in a 2002 Camaro SS

[danachevroletfor1967]

Well after getting around 2 feet of snow and losing electricity, cable (TV and internet), and landline phone line (yeah I refuse to give up my old phone) I finally had a chance to full around with the '02 Camaro in the cold garage.
With the battery negative cable disconnected the battery held a charge for 4-5 days. After connecting it again the battery went down to 5 volts in a couple days. The 12V light tester lit up quite a bit when using it to test for battery drain.
I am assuming this means something is draining the battery when the car is off?
Now to the hardest part, trying to find where the drain is.

Thanks again guys for your input and help.