'Slender Man' stabbing suspect's sketches show girl's dark obsession

A teenage stabbing suspect believed a spooky Internet character called Slender Man would kill her whole family unless she first murdered her school friend, a US court has heard.

Anissa Weier told police she feared the Slender Man's wrath after reading online horror stories about the tall faceless creature.

Her notebooks, presented to the court, showed her drawings of the paranormal figure and a list of supplies, presumably the items she thought she would need in her alleged plot to attack her friend, including a "map of forest" and "weapons (kitchen knife)."

Other excerpts said, "he still sees you" and "safer dead", ABC News reports.

Weier and her co-accused, Morgan Geyser, told police they made a deal with the Slender Man that their families would be safe from danger if they murdered 12-year-old Peyton Leutner.

Weier and Geyser are accused of luring their friend into woodlands in Waukesha, Wisconsin during a game of hide-and-seek and stabbed her 19 times in May last year, the court heard.

Both suspects, who were 12 at the time of the attack, are charged as adults with first-degree intentional attempted homicide.

Neither girl has entered a plea.

Their lawyers argued yesterday the girls should be charged as juveniles in a children's court. A judge is expected to make a decision on that today.