My experience resonates with Ontario's Mom. IIRC, it was 90+ degrees with a heat index of 106. Wearing a tee shirt (any shirt exposing arms) and being in a cornfield getting scratchy, itchy and cuts added to his rage that his plan wasn't going accordingly. I think he became enraged and violent and no doubt blamed her for his pleasure script being ruined.
I don't see any evidence that he dragged her into the cornfield. The corn was pushed downward in an outward direction. He drug her out.
He was not able to seize her and take her to his horror house. I believe he killed her there. Thus he had to dispose of her body quickly and in a manner he was not prepared for. I think he had planned on having her in his possession for a few days. So he had to get rid of the main body of evidence first.
His plan was further thrown off by the quick response of searchers so that he could not go back during daylight to retrieve the evidence left at the scene of the abduction.
His anger and frustration were so intense that he could not think logically and thus concocted his implausible story, placing himself at the scene in trying to explain it. Nor did he anticipate the possibility of the rapid and timely search on his property.
Ne never thought that he would be caught from 1990 (or before) to present.
I think she outsmarted him and fought him which he was unprepared for and disrupted his plan. And he exploded into violence. To him, she was a "thing" and inferior, her assertiveness was a direct challenge. And he reacted to that. For a brief few moments she changed the power dynamics. He responded in a fury. And then remained furious that she robbed him from his plans for her in his lair. Subconsciously he would have to re-establish his dominance.
If things had not gone so very wrong...she might have been found in his horror house..
God bless her family, boyfriend, friends, all who knew her and the community that is irreparably traumatized.
May Sierah rest in gentle peace.