The pin inside the key can be removed and put into a new key that has been cut. They are interchangable on Mercs and lots of other vehicles.
When they stole the van, they will have bypassed the immobiliser first, and then used the key they have.
So either they had an original key in their possesion at some time (garage-dealer-towbar-roofrack fitter) of which they stole the transponder to put in another key or
They bypassed the immobiliser to use a key without a transponder (Is that possible?) If so why do we even have immobilisers?
Or if the Mercedes has a fixed code key rather than a rolling code key they read the code using a device and then programmed a newly cut key with that code.
doesn't the Mercedes have a rolling code set up?
If it does then according to the key cutting websites it needs the vehicle to programme the key.
The van had been into a garage in town about 4 months ago. However, they had our business address not Adam's home address so if it were someone from the garage, they would also have to find the van in a village 7 miles from our unit.
I have posted a little more in the CC about who nicked it, believe it or not it was a local ***** (yes BA a *****). We've since been told that Sprinter vans have been disappearing from the local area and possibly cut up for export.