I'll bite but I don't believe it.

There are, on the Gotham map, 28 red hand drawn circles/squares.

There are 20 circles, 6 squares and 2 keys at the bottom.

The recent shooting had 28 victims including the killer.

There were 20 children, 6 adults at the school and the 2 related mother and son.

The key shows a circle and then a circle with a U outline. The U and V is often referred to in symbolism as a womb / uterus. This would make the circle the shooter and the circle and the U as the mother.