Two dates are certain in the deeply disturbing product tampering case that hit the news this week.

On Aug. 14, the Sanford Hannaford supermarket received complaints from two customers who reported finding what looked like razor blades in the balls of fresh pizza they had recently purchased.

On Oct. 11, police in Dover, New Hampshire, arrested Nicholas R. Mitchell and charged him with tampering with pizza dough that had been made by his former employer, It’ll Be Pizza, in Scarborough.

What happened between those two dates, however, is not so clear. In fact, it’s more clear what didn’t happen.

Hannaford has acknowledged that it did not report the apparent tampering in Sanford to the police. The supermarket also did not warn its customers.

Apparently, Hannaford didn’t check in with It’ll Be Pizza, either, because if it had, the grocery retailer would have likely found out that the dough maker had a good idea of who might be out to hurt them.

Mitchell worked as a forklift driver for It’ll Be Pizza until he was fired in June. Since then, the company received more than 100 harassing phone calls that it was able to trace to a phone registered to Mitchell.

In the last few weeks, razor blades or blade fragments were found in pizza dough made by It’ll Be Pizza (branded as Portland Pie Co.) in Hannaford stores in Saco and Dover. Saco police identified Mitchell as a suspect, and matched him and his car to security camera footage in and outside the Saco store.

Hannaford has recalled all It’ll Be Pizza products from all of its stores, and the recall has been expanded to Shaw’s and Star Market stores in New England.

This is the kind of action we would have expected after the first customer complaint back in August, but nothing happened for almost two months. Hannaford corporate communications issued a statement Wednesday blaming a “a failure within our email system” that prevented the report from reaching the right people in the corporation, but that still leaves questions unanswered.

Did the Sanford store employees recognize that they had been a victim of product tampering, or did they write it off as a quality control problem? Did they follow up with the corporate office when they saw that there had been no response?

And most importantly, what is the supermarket chain doing to make sure that nothing like this will happen again?

It’s a relief that no one was injured by the razor blades, but considering how people handle pizza dough, it’s also a lucky break. And it seems unlikely that someone would tamper with products in August and October but not at any time in between. Someone could have been seriously injured in the weeks since the first report was made in Sanford.

Fortunately, this kind of crime is extremely rare. But anonymous violence has the power to terrorize a whole community. If people are going to have confidence in the food supply, we need more transparency than we have seen so far.