I went to the shops earlier. On the way, I saw this beautiful scene:
On my way home, half an hour later:
Note the heartbreaking way snail B can't bear even to look at Snail A's crushed remains. As a Snail Scene Investigator, and judging by the distance between the snails, I can conclude that the murder took place not less than nine minutes ago. That's a 21 minute window. Someone must have seen something.