Yeh I get that, wasn't expecting it to just be dead easy but 3 weeks? Surely you go either side of the river right to the bloody bay checking.
The issue is that it isn't the simple. I'll give a few examples I've heard today already: "
It's only a mile away" Okay - a mile by the crow flies or in the river?
I have an inkling it'll be the former: "
But, they've got sonar." I know Hollywood's depiction of things overstates stuff, but what do people think sonar is?
These aren't large, powerful sets, but rather small sets, which aren't likely to decipher the different between a large tree trunk/branch or other debris.
So, we're talking about a search of a river that's likely over a mile long between the hours of 9am - 4pm. If they searched every day over a three-week period...
... that's close to 74 m to search each day, so imagine if you're searching the river to the mouth. They'll have studied the weather, currents and lay of the river.
As I said earlier, this will be done with little to no visibility, so it's a fingertip search and done properly - no point in redoing it. That's very, very labour-intensive.
Without talking about this case, but as
@tsubaki mentioned, a body can go under the water and not come back up for a period of time if caught in currents or debris.
In most cases, a body that's gone into water will be found when it comes back up; that's maybe not what people want to hear, yet that's how it actually is.
Now I know the Mersey is hugely different (large, tidal estuary), but they've found a few bodies over the years under the Pier Head that have been there for ages.
But I'm digressing. My overarching point is that the cops may have made mistakes, and if they have then they will eventually, and rightfully, get criticised.
However, most of the criticism from people is completely unfounded and based on little subject knowledge, with the press and social media fuelling it all.
I totally get the family believing she wasn't in the river because ultimately to admit that the river was the most likely scenario is to accept that she's likely dead.
Who'd want to do that? It's reasonable for them to have hope... but the rest of the dross out there who've chatted absolute unsubstantiated wham can do one.