I think you must mean, hasn't been answered in public. I certainly don't know -- and I strongly suspect you don't know either -- what Hatfield may have said in answer to such a question during interrogation.
NO INNOCENT PERSON would have a 72 hour alibi. Innocent people do not have specific memories and records of where they were when a crime was committed unless they are creatures of habit who always do exactly the same things with the same people. The first thing I would do to a person with a pat alibi is give them 10 other time and date periods to alibi. If they can't cover other times as well as the crime time, it is likely they are guilty. It is very rare for an innocent person to have much of an alibi. Why should he... He didn't even know he would need one.
The first thing a real criminal does is try to create an alibi. Only the real criminal knows he will need an iron clad alibi for a long period of time. Innocent people ususally have big gaps that they can't account for with witnesses, logs or records.
Innocent people almost never have an alibi for that long a time period..... But you knew that.
A person smart enough to do this kind of science would not leave clues to some town or school near where he lived. A smart scientists would use a name or site common to millions. A smart criminal knows he will leave clues. So he or she purposely leaves tons of fake clues that point at thousands or millions of people.
A Smart criminal does not try to leave zero clues. He tries to leave dozens or hundreds of clues pointing in all directions. Then the law can't tell real clues from fake clues.