I hope no one is blaming the operator for the homicide, but speaking as a 911 dispatcher I think the ball got dropped in this case. 

There are multiple avenues that the operator/ dispatcher (depending on how their roles are divided) could have pursued to determine the address of the caller. They could have replayed the 911 tape. They could have called the 911 caller back. They could have checked in house/ public records for the phone number. If it was a cell phone, they could have contacted the service provider and obtained subscriber information.

It gets busy sometimes and things can fall through the cracks, but given the nature of the call and the fact that two officers spent 30 minutes looking for the address I think more should have been done.

Edit: I skimmed the article and missed that the suspect called from a 911 phone. My other points still stand. If someone calls in reporting they're going to commit a murder and your officers can't find the address you better get a supervisor to pull the recording.