What's your nickname? Pitbull?

No, you're right. "We ain't not bein' fooled around by such a Wannabe-Bundy like he is". Of course it's one of his tricks. He doesn't make many mistakes though. And it's almost certain that he is not to be found residing in the Nieheim area.
Instead this photo on the left is more likely to show the killer's residence. When I say more likely, it doesn't mean a 100% certainty. But given the facts, that he is a controlling character and none of the calls or text messages have been made from this area, almost pinpoints it. There remains an open question though. Where did he hold his victim? As you can see on the big photo below, the killer's home is in an urban residential area with only 3 to 4 story houses and many potential witnesses.

It always starts with brainstorming

We know where the killer lives, we know where his family lives, we might even know where his Ex-wife with his 2 kids live. Still we don't know where he held Frauke for 5 days. We won't be able to do that, if we don't know what he does for a living. Remember the van? Is it likely that he owns such a vehicle just to do abductions? Or is it more likely that this car is used by him more in a professional way? Hmm, what might that look like?
These cars are used by:
-Postal service companies
-Craftsmen, like from small repair companies, electricians, heating installer, plumber, painter; cleaner
-Freight forwarder, moving services
-Garages for cars and motorcycles
You remember there were many garages where 3 of the 6 calls have been made. Let's check out each one of them.

After checking out every garage in the business park

You checked out every single garage and car dealer in the business area to no avail and you just wanted to call it a day, when you drive by a company that looks interesting. First: They have several of the cars mentioned earlier. Second: It's their field of work, cleaning hospitals. Is this a coincidence? The victim worked in a hospital. To this point we can't do anything, but get our fancy detective notepad out and write down the companies name James*-Group. Maybe someday a witness will come forward who has seen one of their cars.
*name changed

"The secrets of the cleaner"

This is it, the holy chamber, the cathedral, only accessible if you are a consecrated member of the sacred order of the cleaning staff. In the most buildings there's a room mostly located in the basement. Decorated with odd metal furniture designed for its functionality. And of course the ECC3000, The Mercedes among the cleaning trolleys. Proudly it presents its impressive arsenal of floor mops, brooms and chemical cleaners. You think of the time frames when most calls were made, late at night. This is when cleaners do their regular work in empty buildings. The killer feels safe in these circumstances. This trace is definitely the best so far. Let's keep it in mind. 

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