Police should have attempted to contact SOMEBODY before closing the call
They did. From the article:
The officers that received the call arrived at the location and knocked at the door. When no one answered, they requested a call-back of the caller which went to voicemail. They also checked the perimeter windows of the home and spoke with neighbors who reported that they had not heard any disturbance.
They knocked and didn’t get any answer. They called back and didn’t get any answer. They looked in the windows and didn’t see anything. They talked to the neighbors, who denied hearing or seeing anything. I can’t think of anything else they could have done, short of breaking into the home, and at that point they couldn’t even be sure they had the right address.
This is just another illustration of the fact that the police can’t always protect you – even when they’re trying to.