Who betrayed Ned Stark?

Who betrayed Ned Stark? Littlefinger betrayed Ned Stark, causing him to be executed by King Joffery. Littlefinger told Catelyn that the catspaw Valyrian steel dagger used in the attempted assassination of Bran belonged to Tyrion, when in fact Baelish sent both the dagger and the assassin.

Littlefinger betrayed Ned Stark, causing him to be executed by King Joffery. Littlefinger told Catelyn that the catspaw Valyrian steel dagger used in the attempted assassination of Bran belonged to Tyrion, when in fact Baelish sent both the dagger and the assassin.