Stupidity: Kale screams for Ronnie after he sees the image of the club girl on the videotape, and Ronnie proceeds to just stand there and doesn't even bother to go up to Kale to see what is wrong. Had Ronnie gone up the stairs to Kale, then there was a likely chance that they could escape from Turner easily.
Stupidity: It was very idiotic of Turner, who is an experienced serial killer, to not only knock out and take Julie prisoner, but to attack Kale as well, considering the recent circumstances. The police and Julie didn't believe Kale, and Turner suddenly goes on a rampage? He took a huge risk when he attacked Kale and could have very easily blown his cover.
Answer: He noticed Ashley following him and left the shovel behind, confronting her at her car later and threatening her.
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