I wonder whether readers learning about the "painstaking trawl through mobile phone records" realize that those records are only a (vague) location, a time and a duration and that nothing proves that the cell phone user was the cell phone owner (burglars burgle eventually cellphones).
They don't have to be in a vague location. It depends on number of towers and how far the towers are from the apartment.
How far the phone is from the tower can be calculated, in modern methods maybe even better..
SY probably has a pretty good software as mobile pinging would be an extremely useful tool in an investigation.
I can imagine there are much more sophisticated software provided to the police.
For example it is known that Eduard Snowden put his phone in a fridge.. even if it was switched off ..as apparently according to him,. only if inside a fridge or microwave a phone cannot be located.
Also I know of a case in London, where a girl was held in an apartment against her will and the police pinpointed her whereabouts just by her mobile phone which was switched on in her bag. They knew which apartment in a building full of apartments she was in.
So, by knowing this, I believe the police is able to trace the phone user to exact whereabouts.