In (one's) midst phrase
In, surrounded by, or in the middle a specific group of people.
He was the only one to survive in their midst after the ship sunk.
If there hadn't been a traitor in our midst, why would our secret be disclosed?
The origin of this phrase is not clear.
A legal matter that is very easy to solve
The house owners didn't lock the doors before going out, and that's why they got broken in. This is an open and shut case.