What evidence?
So this phone. I assume it didn't pop in to existence on 3rd May 2007. So there's a call log stretching back from the minute he registered it (under his own name, bizarrely).
Fritz (is that racist?) would have picked through that like a crow picking sweetcorn out of pig sh1t. Meticulous. No kernels left unpicked. We can guarantee that.
In addition, this phone log would have been forensically sifted with the most advanced technology available - think CSI Paderborn. Every contact would have been traced, interviewed, corroborated, cross-referenced. Like Tommy Lee Jones looking for Richard Kimble that time. Relentless. Exhausting just watching.
They gleaned two pieces of data - the phone pinged locally at the time and he received a call from someone around the time. That's it, as far as we know, given that HCW actually played that card 20 months ago.
What has that given them? Nowt. The person who called him has not been traced, clearly. I actually think that was a burner phone and they tried to trace it but hit a dead end. I also think that person is probably dead. The fact that none of CB's confederates who took the money and grassed knew of this person or admitted to being him / her, also means that, in all probability, is in the wind or dead or a hide and seek champion.
Why? Well they also have his / her phone number, so would have investigated it as thoroughly. The fact that this has also drawn a blank is very telling and must be a source of some confusion.