Season 1, Episode 03: Rest in Pain — April 26–May 02, 1990
The townsfolk of Twin Peaks gather for Laura Palmer's funeral; Cooper
interprets his dream about the killer; Truman reveals to Cooper the secret of
the Bookhouse Boys.
A refinement to the previous theory:
Laura was actually working for the Bookhouse gang (sheriff, etc.).
That is why she had the money and cocaine in the safe deposit box. The money
had been given to her by the sheriff. She was supposed to infiltrate Leo's
evil gang, but things went too far and "She's DEAD".
[src]