Close to two weeks after mum-of-two Nicola Bulley disappeared while walking her dog on a riverside path, a number of key questions remain unanswered.
Nicola was last seen on January 27 by the River Wyre in St Michael's on Wyre, Lancashire, where she was on her usual dog walk after dropping her two daughters, aged six and nine, off at school.
Her phone was found on a bench by the waterside and had recently connected to a work call. Her dog Willow was running loose.
Police launched an extensive search of the area and said their "main working hypothesis" was that she fell in a river but a body has not yet been found.
As former Metropolitan Police Detective Chief Inspector Peter Kirkham has put forward a number of key questions he believes need to be answered.
The former police officer writes:
As the investigation approaches its third week, experienced detectives will have realised that this case is not going to be easily solved. In many major investigations the enquiry team know at least the main facts within the first week or two, if not sooner.
Of course there is always lots more work to do, knitting it all together and filling in any gaps, but, broadly speaking, officers know what happened.
There are always the “exceptions which prove the rule” - the cases which take longer, sometimes very much longer, to get to grips with and understand.
You take an example very well known to the public, think of the Madeleine McCann case. There we are many years into the investigation and there is still a huge hole at the centre of the known facts.
That hole includes knowing how Madeline came to leave her bed in the family’s holiday apartment…and, without knowing that, pretty much everything is an opinion or the statistically most likely option rather than a fact.
The Lancashire Police enquiry team will be desperate to avoid the same fate. The next few days and weeks will be essential to ensure every tiny piece of evidence that can be found and secured is found and secured.
Undoubtedly, by now, pretty much all the evidence that is there to be found will have been found and secured and genuinely new information and insights will be becoming fewer and fewer.
To try to make the best analysis of the available evidence officers will be ensuring that they understand the reliability of each piece of the evidence.
They will be looking for the pieces that are absolutely rock solid so that they can use them as starting points, using them to build out and (hopefully!) fill in the gaps in the account of what happened to Nicola.
1. If Nicola did end up in the river, where and when would she surface and would it be likely that she would be spotted?
Detectives will have taken expert evidence from academics and others who spend their lives studying the movement of water and its impact on items such as a body which are in it.
This is a hugely complex area, and there are many unknown (and unknowable) factors in play. As a result the information given to officers will not be particularly reliable or precise. In most cases, a body will emerge within about five to ten days, but the margin for error is large.
As a result the police will need to keep searching and re-searching a very long stretch of the River Wyre for some time. The investigators will be desperate not to miss the body if it does emerge as they know it will be critical to the case.
2. What does the location at which the dog was found tell us about where Nicola disappeared?
As we know from the many, many stories of loyal dogs staying with their owners when they have fallen ill or died, as a general rule they won’t go far. They will wait near the point they last saw their owner.
Experts in canine behaviour will be able to give an estimate of how reliable this information is likely to be in this particular case.
I expect officers will conclude that Nicola disappeared near the bench where Willow was found, with Willow simply not seeing where she went and so staying around that spot. This is likely to be crucial in assessing the different hypotheses.
3. Could Nicola simply have walked out of the riverside area around the bench by herself?
Police have said there are only three paths, with two covered by CCTV, but how good is that footage? Could she have slipped out unseen?
The fact Willow was still there suggests it is reasonable to conclude she didn’t leave the area, but just how reliable is the actual evidence?
4. How reliable are the witness accounts saying they saw Nicola in that riverside area?
There are at least two witnesses who seem to have actually known Nicola to some extent. These accounts would presumably be confirmed to some extent by at least a small part of the CCTV footage.
This makes things more reliable and, of course, Willow was found there and who but Nicola would have taken her into the area. This will be amongst the most reliable facts and will be a key part of the foundation of the investigation.
5. Can the technical evidence from Nicola’s phone, especially that around the time it was put on the bench, be relied upon?
To be honest, I would view the information with a critical eye. Technical data (from any source) is notorious for being potentially misleading as systems are so complex that few, if any, technicians and engineers know precisely how all data is gathered and processed within the system.
Personally I would not consider this information particularly reliable and would seek corroboration from other sources if at all possible.
6. Was there anyone else in Nicola’s life who may have influenced her and how events developed?
Very many of us have secret aspects to our lives that are not fully known to those closest to us. Police will be scrutinising every aspect of Nicola’s life going back months or even years.
It is essential they know literally everything there is to know.
7. Finally, and perhaps most crucially of all, the investigators will need to know whether there is any chance that Nicola was removed from the riverside area by a third party.
They will consider whether any detailed pre-planning could have made this possible and whether Nicola may have been persuaded to leave with them by some subterfuge.
The police clearly currently believe this could not have happened but, if it could be done in some way it would reinvigorate the hypothesis that Nicola was taken and suddenly the potential involvement of a third party for malicious or other reasons is back on the table."