Battery drain - from starter?

Hello Experts,

I have a VW Westfalia. That's the first problem. It has a battery drain.
I have isolated all the wires to the battery's positive by installing a switch in line. Except for the Wire to the starter. A couple of days later without starting the van. The battery is dead. So my drain must be starter related. How can I test this with a simple multi-meter?

Thanks.