This security measure requires pinning the inner & outer window sashes together. You will need to acquire a couple of ¼ X 3 inch eye bolts for each single & double hung window that you need to secure.
With the window fully closed, drill ¼ inch diameter holes at a slight downward angle through the top corners of the inner sash into the bottom rail of the outer sash.
It is extremely important that you do not drill too close to the windows pane where you would hit the glass or damage its thermal seal.
It is also important not to drill more than ¾ of the way into the outer sash.