The Resurrection of Jason Voorhees
The Dark Ones were an evil tribe of necromancers who traveled to Hell, studied demons, and wrote a book called the Necronomicon Ex-Mortis. Roughly translated: Book of the Dead. It had the power to raise the dead as skeletons or zombies called Deadites, or awaken the spirits of Kandarian demons who died long ago, as a single evil force.
One day, a Dark One named Zorf decided to experiment with another power of the Necronomicon: Time travel. He turned to a page and recited an incantation. Instantly he vanished.
He reappeared in the year 1957 and jumped. A woman stood before him. Her name was Pamela Voorhees. They stood at the edge of a lake.
"What's going on?" said Mrs. Voorhees.
"I am one of the Dark Ones," said Zorf. "I shall destroy you."
"Wait!" said Mrs. Voorhees. "How did you just appear out of thin air like that?"
"Because I have a book of magic powers. The Book of the Dead."
"In that case, can you use it to bring back my son? He drowned in Crystal Lake a few weeks ago. The camp counselors weren't paying attention. Jason should have been watched every minute!"
"Why would I do that?" said Zorf.
"I want my vengeance on the camp counselors," said Mrs. Voorhees. "If anything should happen to me, he will finish my work for me."
"I won't give you this book," said Zorf. "It belongs to our leader. I should be going back to my time now."
Mrs. Voorhees stabbed Zorf in the stomach with the knife. She turned the pages and found one for resurrecting the dead. It would bring him back as a Deadite, very difficult to kill. If he was somehow killed, a bolt of lightning could bring him back and make him stronger, to the point of being unable to die without someone in his bloodline stabbing him in the heart with a Kandarian dagger.
"Klaatu verata nikto!" said Mrs. Voorhees.
Jason rose up out of the water.
Meanwhile, in the past, the rest of the Dark Ones were worried. Zorf hadn't returned.
Their leader, El Keris, looked into the future using a magic spell he knew. He saw Mrs. Voorhees with the Necronomicon in the Voorhees house. He watched further into the future.
"We can't go yet," said El Keris. "The Necronomicon is with a serial killer. She killed Zorf and she'll do the same to us if we get near. Her son is now a Deadite and if we cross him we may never come out alive."
He watched Jessica Kimble stab Jason in the heart with a Kandarian dagger, and he was dragged to hell.
"There," he said. "After Jason goes to hell and those two people walk away, that's our cue to go to the house and recover the Necronomicon."
The potions master put together a potion, and Alastair, one of the Dark Ones, drank it. He said "Klaatu verata nikto", and entered the future. He found the Necronomicon in the Voorhees house, with both Mrs. Voorhees and Jason dead no one could stop him. He drank another potion given to him and returned to the future.
The Dark Ones kept the Necronomicon resting in a cemetery whenever they were not using it, guarded by two fakes.
Years later, a demon slayer wielding a Kandarian dagger battled the Dark Ones and killed them all. He stabbed El Keris in the heart last. The Necronomicon remained in its resting place, at a cemetery, until it mysteriously disappeared in the year 1300 AD.
This story explains my interpretation on how the Necronomicon was in the Voorhees house years after it was destroyed, and how there seems to be no gap between its location in Army of Darkness and its being taken to the house in The Evil Dead.