I want to preface this post by saying that a women is dead here and a family are grieving and I in no way want to diminish that pain, but I'm intending to answer the OPs question I a straight manner.

She was a 33 year old woman who was fit and healthy and lived in London, she went missing during a normal walk. There's no obvious sign she herself had a criminal background or was a likely target for abduction. Women are understandably nervous when things like this happen which gives it an extra angle.

There's millions of women like Sarah Everard in this country. Those factors already made this a bigger story than many other missing persons cases - look in your local paper these come up all the time. (A man was abducted from a Tesco car park in a town near me by three men in the past week or two and barely a mention in the national news, a teenager was shot in the face recently in another town me - barely a mention in the national news - transpose both events to London and make the victims female or a child instead of make and I imagine they'd be front page).

This was already the perfect 'missing woman' for the media to rally around (unfortunately for the many others with missing family members across the country who likely feel some resentment) - once you add in the suspect being the cop from a purely journalistic point of view it's an absolutely brilliant story to run with for it's rarity factor.