Bubbles

9
Because :  (sum of numbers in two corners of base of the triangle )- (number in the other corner)= number inside the triangle
In figure1 : (9+7)-4 = 12
In figure2: (4+1)-1=5
In figure3: (6+5)-2=9

The woman   is killed by the person.  While coming,  he unlocked the door from outside and killed the  woman, and lock the door
from inside.  So the door was still locked  when the doctor  had arrived.

The  robber wanted to die from  a weapon,  made up of  king’s spinal card !!!!