What's the Point of Self-Preservation?

Fresno in 1935 was a fairly safe place except there had been a recent series of break-ins so burglaries, right, including at the stammer house twice. He couldn't identify somebody dressed in black who had tried to break into a house and listen to this, whoever did that to Walter's house to the victim's house had cut the telephone lines on the last one. This is like a half century before 911. So the cutting the phone lines was to prevent victims inside the house from being able to call the operator in order to get help to respond. Yep. It's smart.