Alvin R. Dyer, Who Am I?, p.235 - 236
Recognizing their unembodied condition, and their ultimate doom without a tabernacle of flesh and bone, evil spirits seek to take possession of the natural bodies of the sons and daughters of God, and even the bodies of animals. Scriptural accounts bear record of these attempts. All of this simply bears out the foreknowledge of God's design for man which these evil spirits have retained.
President Rudger Clawson, Conference Report, April 1939, Church of the Air Broadcast, p.118
Their eagerness to secure bodies is so great that in many cases they endeavor to steal the bodies of the more favored spirits, and when these evil spirits enter into and take possession of the bodies of others we say of those afflicted that they are possessed by evil spirits. They can only be subdued and cast out of stolen bodies by those members of Christ's Church who are under divine authority.
Legrand Richards, A Marvelous Work and a Wonder, p.293
When Jesus had cast out the evil spirit from the man whom no man could bind with chains, he asked his name, and the spirit replied, "Legion: for we are many." (See Mark 5:2-9.) Upon being commanded to leave the body of the man who was possessed, the evil spirits asked the privilege of entering the bodies of swine feeding in the field, and when their request was granted, "the herd ran violently down a steep place into the sea." (Mark 5:13.) It is so desirable to have a body that these evil spirits, who had forfeited the right to bodies of their own, were even willing to enter the bodies of swine.
The Contributor, Volume 7
A company of two hundred and forty-nine males, and two hundred and sixty-six females... in Kirtland, on the fifth of July, 1838; and the next day started for Missouri. The journey was long and tedious; many difficulties were encountered and obstacles overcome. A spirit of murmuring was frequently manifest, much sickness was among them, and because of their disobedience, evil spirits plagued them by getting possession of their bodies.
Evil Spirits Can Possess Bodies of Mortals
Alvin R. Dyer, The Meaning of Truth, rev. ed., p.149-150
...Another incident of noteworthy reference, giving some evidence of the number of evil spirits that roam the earth, concerns two maniacs who were sorely tormented by evil spirits. One of these at least, according to the Gospels, had been bound with fetters and chains, but, with demoniac power had broken them away and had fled to the mountains to live among the tombs like an animal. Night and day his weird and terrifying shrieks could be heard. Seeing Jesus, the poor creature ran toward and was prostrate before him, crying out with a loud voice:
What have I to do with thee, Jesus, thou Son of the most high God?
Jesus commanded the evil spirits to leave. One or more of them through the voice of the man, pleaded to be left alone, and with blasphemous presumption exclaimed:
I adjure thee by God, that thou torment me not- Art thou come hither to torment us before the time?
The demons, by whom the man was possessed and controlled, recognized the Master, whom they knew they had to obey; but they pleaded to be left alone until the decreed time of their final punishment.
Joseph Fielding Smith, Doctrines of Salvation, 3 vols., edited by Bruce R. McConkie, 1:, p.65
DEVILS STEAL BODIES. At times these fallen spirits steal possession of the bodies of men and women, overpowering the spirit who has rightful ownership. They realize what they have lost and are willing, when opportunity is given them, of possessing bodies of lower animals, so anxious are they to be clothed with flesh even for a season. On one occasion a legion of these evil spirits, when cast out by the Lord, asked the privilege of entering the bodies of a herd of swine. Out of Mary Magdalene the Lord cast seven devils. These evil spirits know the Lord from the knowledge and experience they obtained in the heavens before their banishment for rebellion. They called him by name when he disturbed them in their stolen habitations, saying: "Thou art Christ the Son of God, . . . for they knew that he was Christ."