Dexter: Season 1, Episode 12

1 - 12: Born Free

Doakes and LaGuerta begin to suspect that Rudy is the Ice Truck Killer, while Dexter finds a suspicious picture of the shipping container where his mother was killed. A call from her ex-husband makes Rita suspicious of Dexter and his behavior. Dexter recalls that Rudy is in fact his biological brother, whose real name is Brian Moser. Brian intends to kill Debra with Dexter in a reunion with his true family, but Dexter stops him. As the police close in, Brian escapes and Dexter is left with Debra, appearing to have saved her. The same night, Brian breaks into Dexter's apartment and attempts to stab Debra, but Dexter captures him. After an emotionally charged conversation, Dexter slices his brother's throat and leaves him upside down to drain, staging it as a suicide, while wondering what would happen if everyone knew the truth about him.