That means “through the entire line,” as in all down the line, or by all involved, in this case.
So, let’s sum up this Jaber al-Bakr case in Germany: First of all, you have a German intelligence service (BND) that isn’t in the position to know about this guy or his plans on its own – that evil US-Amerikan NSA had to give them the tip. Then you’ve got policemen who let this guy get away during their raid. After that he gets captured, tied up and turned in to the police by three Syrian refugees. And to top it off, the authorities then guarding him let him commit suicide in his cell.
All in all, some top-notch work. All down the line. By all involved.
Einem Medienbericht zufolge hat ein US-Geheimdienst einen entscheidenden Hinweis auf den Terrorverdächtigen Dschaber al Bakr geliefert.