Do Intelligence Agencies work under an “allowable body count” paradigm?

From The Last English Prince:

Germany has a known terror suspect. He is on a deportation list but remains in the wild. He runs free. Lives like a free man. And apparently, is not a tethered goat. 

If it is true that this man is responsible for the Christmas Market lorry attack in Berlin, then is the body count within allowable parameters for German Intelligence? 

Is this the nasty little secret that needs to be addressed: allowable civilian deaths in pursuit of intelligence? 

Do we do the same thing? 

A risk-benefit paradigm should NEVER include allowable collateral damage of citizens. Berlin Terror Suspect Rumors are afloat that a child was crushed under the wheels of the lorry. 

Who, then, is legally responsible for the death of this child? 

I consider leaving known terror suspects on the street a criminal act which should be punishable with incarceration. 

GO READ THE WHOLE THING.