Each of these sequences should suggest a different killer and motive. You can watch any monitor as the last. If you've been following a story successfully, talking to Frankie in the Fly Eye will yield some useful information.
ballroom / Communications / Laboratory / ballroom / Communications / ballroom / ballroom
Laboratory / playroom / Communications / Communications / Communications / ballroom / ballroom (and Alien Zoo to discover how Greg's hair turned white)
playroom / playroom / Alien Zoo / Communications / Communications / Communications / playroom
This sequence of monitors shows all the haunting phenomena. The same phenomenon occurs in Communications twice.
playroom / any room / Communications / Alien Zoo / ballroom / Communications / playroom