A few weeks ago, on the topic of evil spirits encountered by missionaries in the Southwestern States Mission, I wrote: “There are a few acknowledgments of the possibility of possession, but no instances of it.” Now, after a trip to the Church History Library, the possession record is slightly more complicated. 
In the original post I cited Mission President Duffin’ diary entry about a Holiness manifestation that interrupted a sermon he gave in 1904 in St Louis. Duffin “did not question but what she had the spirit but thought it was of the devil,” though in his diary he downplayed the supernatural. 
Sister Josephine Cluff, a missionary assigned to St Louis, was also present:
… An incident happened which I shall always remember, as it was the first demonstration of a religious kind—or any other kind in fact I was ever an eyewitness to, and trust I may never see again. Pres. Rulon S Wells had spoken to us upon the application of Scripture, and his sermon was beautiful — I could have listened longer though he had the floor for more than an hour. Then Bro. Cuddingham then spoke on obedience for only a short time. The choir sang “The Spirit of God &c,” when Pres. Duffin arose. It was the first time we have been privileged to hear him since our arrival in St. Louis, and it was with pleasant expectancy that we saw him take the stand.
He had fairly begun on the Atonement when an unearthly shriek resounded through the house, and a rather large woman sprang from her seat, and marching up to the front and gesticulating wildly, cried out, “I am saved.” “Only Jesus can save” &c. Some of the men tried to stop her, but it was of no use. She continued her marching and yelling and crying, sometimes falling to the floor, sometimes kneeling and calling out “Only Jesus can save,” until she was in a state of perspiration and exhaustion, when her husband finally got her to go home.
This event seemed to put an end to our good spirits, and we sang and were dismissed. This is a testimony to me of the evil power, something I never thought to see rational beings engaged in possessed of. There had been a most lovely, peaceful feeling up to that time, and everyone seemed fed and strengthened by Bro. Wells’ sermon, and were just waiting to hear something more of good from our beloved president. Perhaps Old Satan thought we were enjoying too much of the Spirit of the Lord. The woman I speak of was a German and belonged to the Methodist Church. … 
If I understand correctly, Holiness grew out of Methodism, so there isn’t necessarily a conflict between Duffin categorizing the woman as “Holiness” and Cluff using “Methodist.”
Cluff’s replacing of “engaged in” with “possessed of” points to a loss of agency, and might even suggest “possession,” but her use of “the evil power” suggests something less total.  Like other missionaries of the time, Sister Cluff put satanic power in opposition to rationality. 
The “Southwestern States Mission” series uses the diaries of six missionaries who served in eastern Texas around 1900 to illustrate aspects of Mormon material culture, lived religion, and social History. The missionaries are Mission President Duffin and Elders Brooks, Clark, Folkman, Forsha, and Jones. The series is inspired by Ardis Parshall’s serial posting of the missionary diary of Willard Larson Jones at Keepapitchinin. Previous installment here.
 Although I generally root for the other team, I confess a wee bit of disappointment that Satan’s minions were slacking in my time and area of study.
Shout-outs to folks I saw at the library: Paul Reeve, Ardis Parshall, Jenny St Clair, Brett Dowdle, Brittany Chapman, and, of course, the Church Service Missionaries.
 “… At night held meeting in Plumers hall at which Prest. [President] Rulon S. Wells and Brother Luddenham of Salt Lake were the principal speakers. I had just commenced to speak for a few moments when a woman belonging to the people called the “Holiness” people jumped up from her seat and clapping her hands and shouting ran around the room frightening a number of the women present. I spoke to her husband and another man with whom she came to the meeting to take care of her when the silly fellow replied: “Don’t touch her she has the spirit.” I did not question but what she had the spirit but thought it was of the devil. Finally we got her out of the room when I spoke a few words to quiet the feelings of the people and we sang a song and dismissed the meeting” (Duffin, 1904 Jul 10 Sun); this text is emended for readability, etc; the original is available online at the Mormon Missionary Diaries database [p 137-8]).
 I’m pretty stoked about the addition of a sister-missionary diary to my study. Josephine C Kimball journal [Josephine Cluff Jones Kimball 1860-1922], Church History Library (CHL), MS 23321, entry for 1904 July 11; paragraphing mine. Sister Cluff had been married to John “William” Jones; they divorced, probably in 1889. She married Andrew Kimball after her mission (and thus became Spencer W Kimball’s step-mother). The first volume of the diary is at the CHL; a transcript of the second volume is here.
 I am not familiar with the academic literature on possession and so am probably butchering the categories. I am using “possession” to mean that a localizable spirit-being with a personality places itself within the host’s body and supplants the host’s personality and/or will and/or bodily control. I am distinguishing “possession” from “remote-control dominance,” wherein the spirit takes control of the host’s body but does not occupy it.
When Duffin wrote that “she had the spirit” but that he “thought it was of the devil,” he seems to analogize “having the spirit of the Lord” and “having the spirit of the devil.” This construct could be read either as enhancing or reducing agency. The respective spirits could magnify latent abilities while leaving the will intact or they could suppress the will in the sense one sometimes hears in present-day Mormon discourse about speaking with the spirit, e.g., “I didn’t know what I was saying during the blessing; the spirit just took over.”
 For example: “We tried to reason with him but he was so full of the spirit of the evil one that we could do nothing with him” (Jones, 1902 Jan 03 Fri).