More Minority Report spoilers:

Hmmm, I rather like Noah's explanation. It would go a long way towards resolving another apparent implausibility in the plot: Why didn't Agatha's flashbacks to her mother's death reveal Burgess's face until the very end? Or why didn't she simply tell Anderton who the killer was? Because she didn't want to reveal the killer's identity until she was assured of enough witnesses to end Pre-Crime for good!

We should write Roger Ebert about this, seriously.