Sudoku Murder rules

The reference. If a clue could be read two ways, this page says which way is meant.

Placement

The board is an N×N grid, from 4×4 up to 9×9. A case has N people, one of them the victim.
Each person stands on exactly one cell. No two people share a row, and no two share a column.
A person can stand on bare floor or on an object you could sit, lie or stand on: chair, armchair, sofa, bed, bench, stool, carpet, rug.
Solid scenery blocks its cell: plant, table, tree, bush, rock, box, bookshelf, fountain, statue, trash bin. It can still appear in clues.

Thick walls split the board into rooms. Every room has a name, and neighbouring rooms have different floors.
A room can hold any number of people, except the victim's room.

The victim's room holds the victim and exactly one other person. That person is the killer.
The victim's card reads "The victim. She was alone with the killer." The victim may carry one more clue.

She was in the top row.	That row. Middle rows are counted from the top: "the second row" is the one under the top row.
He was in the left column.	That column. Middle columns are counted from the left: "the third column from the left".
She was in the Library.	Somewhere inside that room. Some rooms read "on": on the Terrace, on the Stage.
He was not in the Cellar.	Any cell outside that room.
She was on an armchair.	Her cell holds that kind of object.
He was not on a sofa.	His cell does not hold that kind of object. It may hold another one.
She was beside a plant.	At least one cell directly above, below, left or right of hers holds a plant, and that cell is in her room. Diagonals never count.
He was not beside a chair.	No chair directly above, below, left or right of him in his room.
She was in a corner of the room.	Her cell touches her room's walls on two sides that meet: one side and the top or bottom. The edge of the board counts as a wall.
He was not in a corner of the room.	His cell is not such a corner.
He was in the Study with another man.	He was in the Study, and exactly one other man was there too. Women may also be in the room.
She was alone in the room.	Nobody else stood in her room.

Every published case has exactly one solution, and it can be reached step by step without guessing. Our solver proves both before a case goes out.