According to Teresa, JoAnn Bain was killed in the detached garage/shop:
http://files.wmctv.com/TeresaMayestestimony.pdf
Adam had walked into Gary's bedroom and got Jo Ann up. He had her walk out to the shop using the story of Kyliyah sleep-walking, once he got her into the shop, he hit her on the back of the head with a 2 x 4. He said this didn't phase her. Adam said she fought while he was strangling her with a rope with PVC at the ends.
http://files.wmctv.com/TeresaMayestestimony.pdf