The River King (movie, 2005)

Abel Grey is sent to investigate the death of a boy from an exclusive local school, who is found floating in the river. Fearing scandal, the school insists it was suicide. But after discovering from the boy's girlfriend, Carlin, that he was being badly bullied, Abel suspects that a dangerous schoolboy initiation has gone horribly wrong and he secretly solicits the help of a sympathetic teacher, Betsy. He is warned off the investigation by his boss, as the school is a generous benefactor to the Police benevolent fund. Abel, however, cannot let the case go, not only because his own brother committed suicide years before, but also it seems that the spirit of the dead boy is leaving them clues as to what really happened that night.