The Mystery of the Heir of Slytherin's Identity
Harry Potter and the Chamber of SecretsThe school searches for the Heir of Slytherin, with suspicion falling on Harry, Draco, and finally Hagrid, before the true culprit is revealed.
increasing
Bearing strength in each event
decreasing
Suspicion on Harry

The Parselmouth Suspect
The Accusation
After Harry speaks Parseltongue, many students believe he is the Heir. Ernie Macmillan publicly accuses him. Harry's ability to talk to snakes is seen as proof of Dark heritage.
The Isolation
Harry is shunned by many. Even his friends are uneasy. He struggles with the fear that he might be connected to Slytherin.
The Counterargument
Dumbledore later explains that Parseltongue is a gift from Voldemort, not a sign of evil. Harry's choice to be good is what matters.
Suspicion on Draco Malfoy

The Obvious Candidate
The Attitude
Draco's smugness and his father's known dark past make him a prime suspect. He taunts Muggle-borns and seems to enjoy the attacks.
The Investigation
Harry and Ron use Polyjuice to question Draco, but he denies being the Heir. He says his father told him to stay out of it. The investigation yields no confession.
The Red Herring
Draco is not the Heir, but his father is involved. The misdirection leads the trio to waste time, but they gain valuable information about the past.
Suspicion on Hagrid

The Fall Guy
The Past Crime
Tom Riddle's memory shows that Hagrid was expelled for setting a monster loose. Harry briefly believes Hagrid was guilty.
The Arrest
The Ministry arrests Hagrid as the culprit. He is taken to Azkaban. The school believes the attacks are over.
The Vindication
Hagrid is innocent. The real culprit is Tom Riddle's diary. Hagrid's arrest is a miscarriage of justice that is later corrected.
after the Dueling Club, December
throughout the year
after the diary memory, and during his arrest