They might of found tire tracks from a motorcycle in the area of the helmet, screwdriver etc.,
Also someone posted abut none of Ce's blood in the truck, there is plastic sheeting listed in the warrant. He might of laid her on it in the bed of the truck to take her back to his house.
Let's suppose that Worley abducted Sierah at about 6:30 or 7. He pulled her and her bike into the cornfield. He's riding a motorcycle. He can't leave his motorcycle on the road, so he moves that into the cornfield as well. He stays there for two hours with Sierah until it starts to get dark. His phone pings in the area near the bicycle for two hours. It's now roughly 8:30 or 9.
She is reported missing at 11PM and her bicycle is located at midnight.
That leaves 2.5 hours for Worley to travel 8 miles to his home. Sierah is alive and injured. He's not going to leave Sierah there because if she is found, there's probably DNA evidence that will convict him. Furthermore, if she escapes, he's doomed.
He's ready to take Sierah to his property, but he's unable to locate his bloody helmet, screwdriver, sunglasses, and fuses. Still, he doesn't want to remain in the field with her any longer because the longer she is there, the more likely it is that he will be caught.
He very likely took her with him on his motorbike to his home. There is duct tape with his and her DNA on it at his property. There's blood on his motorcycle. If she was bleeding on his motorcycle, she was alive when she was transported to Worley's property. There's blood on his motorcycle helmet. I suspect that is from hitting her hard in the head, possibly while riding his motorcycle - the initial attack.
He very likely secured her in his barn, and then planned to retrieve his belongings in his truck - but - police are now on the road looking for Sierah.
He knows that police have discovered her bicycle, and his bloody helmet. This is most likely when he murdered her and buried her.
When police canvassed his home (was that at 3AM ?? don't remember), he knew that they had found the bike and his helmet, and he attempted to provide a plausible story for why his prints are on the bicycle, and why his belongings are nearby.
That is a scenario that fits the timeline, and the known facts.