The ordinary dagger would have made a wider perforation with a corresponding increase in the blood-flow.

My theory of a round-headed knife is based on the circumstance of a portion of the deceased's pyjama jacket having been carried into the wound.

A sharp-pointed knife would have made a clean cut through the jacket." "I see," said Superintendent Galloway, with a sharp nod.
"Therefore, we may assume, in the case before us,"-- Sir Henry Durwood waved a fat white hand in the direction of the corpse as though he were delivering an anatomical lecture before a class of medical students--"that the victim was killed with a flat, round knife with a round edge, held sideways.

Furthermore, the position of the wound reveals that the blow was too much on the left side to pierce the centre of the heart directly, but was a slanting blow, delivered with such force that it has probably pierced the heart on the _right_ side, causing instant death." "The weapon, then, entered the body in a lateral direction, that is, from left to right ?" asked Colwyn, who had been closely following the specialist's remarks.
"That is what I meant to convey," responded Sir Henry, in his most professional manner.

"The blade entered on the left side, and travelled towards the centre of the body." "From the nature of the wound would you say that the knife entered almost parallel with the ribs, though slanting slightly downwards, in order to pierce the heart on the right side ?" "That would be the general direction, though it is impossible to ascertain, without a postmortem examination, the exact spot where the heart was pierced." "But the wound slants in such a way as to prove that the blow was struck from left to right ?" persisted Colwyn.
"Undoubtedly," responded Sir Henry..