Church President Brigham Young declared:

"If Joseph Smith, Jun., the Prophet, had followed the Spirit of revelation in him he never would have gone to Carthage and never for one moment did he say that he had one particle of light in him after he started back from Montrose to give himself up in Nauvoo."
- A Series of Instructions and Remarks by Brigham Young at a Special Council, Mar. 21, 1858, Brigham Young Papers, Church Archives. Also See: http://webpages.marshall.edu/~brown/suc-pres.html under "24 Jun 1844"

The Prophet Brigham Young made the above statement during several church meetings and felt so strongly about it, that he had his discourse, with the above statement, published as an official church pamphlet and distributed among the members of the Church.

In The Mormon Hierarchy : Origins of Power, Michael Quinn recounts the last days of Smith's life:

1. Smith denounced polygamy, destroyed polygamy revelation
"Smith was, in fact, willing to destroy the original manuscript of the 1843 polygamy revelation. Based on "Many (some of whom are now living)" in Utah, Joseph F. Smith wrote that the prophet "consented for her [Emma Smith] to burn the paper containing the original copy of the revelation." An obscure 1853 publication also reported that the original text of the polygamy revelation "by Joseph Smith's command was burned."" (Quinn page 147) Quinn references Letter of Joseph F. Smith to William E. McLellin, 6 Jan. 1880, fd21, box 5, Scott G. Kenney Papers, Manuscripts Division, Marriott Library.

"Emma Smith remembered that the prophet did more than consent to the revelation's destruction. According to her 1847 account, while alone in their Mansion House bedroom, Smith "told her that the doctrine and practice of polygamy was going to ruin the church" and then he burned the revelation. Clayton's diary shows just before the prophet returned to Emma [that night], he told his secretary to burn the Council of Fifty's minutes. It makes sense that while he was alone with her the night of 23 June 1844, only hours before surrendering for trial, he directed his attention to destroying the written evidence of polygamy." (Quinn page 147) For the Emma quote, Quinn references William E. McLellin letter to Joseph Smith III, 10 Jan. 1861 and July 1872, archives, Reorganized Church of Jesus Christ of Latter-day Saints. For the Clayton reference, Quinn refers to Clayton diary 22 June 1844 with an explanation referring to other Clayton journal entries.

2. Smith ordered apostles to get rid of their garments
"Heber C. Kimball said Smith sent word to the apostles on the east coast to destroy their garments they had received in the endowment since 1842." (Quinn page 147) Quinn references History of the Church 6:519 which mentions the letter, and Heber C. Kimball's diary, 21 Dec. 1845, found in the book "Smith, An Intimate Chronicle, page 224"

3. Smith removed his own garments, instructed other to do the same
"Smith removed his own endowment "robe" or garment before he went to Carthage Jail and told those with him to do likewise. His nephew Joseph F. Smith later explained, "When Willard Richards was solicited [by Smith] to do the same, he declined, and it seems little less than marvelous that he was preserved without so much as a bullet piercing his garments."" (Quinn page 146) Quinn references Heber J. Grant journal sheets, 7 June 1907, LDS Archives.

4. In Carthage Jail, Smith drank wine
“Before the jailor came in, his boy brought in some water, and said the guard wanted some wine. Joseph gave Dr. Richards two dollars to give the guard; but the guard said one was enough, and would take no more. “The guard immediately sent for a bottle of wine, pipes, and two small papers of tobacco; and one of the guards brought them into the jail soon after the jailor went out. Dr. Richards uncorked the bottle, and presented a glass to Joseph, who tasted, as brother and the Doctor, and the bottle was then given to the guard, who turned to go out.” (History of the Church, Vol. 6, page 616)

"Sometime after dinner we sent for some wine. It has been reported by some that this was taken as a sacrament. It was no such thing,; our spirits were generally dull and heavy, and it was sent for to revive us.... I believe we all drank of the wine, and gave some to one or two of the prison guards." (John Taylor, in History of the Church, Vol. 7, page 101)

5. Smith sent an order to the Mormon Nauvoo Legion to attack Carthage jail “immediately” to free him
"The morning of 27 June, Smith sent an order (in his own handwriting) to Major-General Jonathan Dunham to lead the Nauvoo Legion in a military attack on Carthage "immediately" to free the prisoners. Dunham realized that such an assault by the Nauvoo Legion would result in two blood baths - one in Carthage and another when anti-Mormons (and probably the Illinois militia) retaliated by laying siege to Nauvoo for insurrection. To avoid civil war and the destruction of Nauvoo's population, Dunham refused to obey the order and did not notify Smith of his decision. One of his lieutenants, a former Danite, later complained that Dunham "did not let a single mortal know that he had received such orders (from Smith)."

"[Later that same day] Around 5 p.m., more than 250 men approached the Carthage Jail. When informed of this by the panicky jailer, Joseph Smith replied: "Don't trouble yourself, they have come to rescue me." (Quinn, Page 141) Smith quickly discovered that the mob wasn't his rescue army. After exchanging gunfire with the mob, Smith was killed.

6. Smith did not give his life, or die as an innocent martyr
Smith shot three men the night of his death at Carthage Jail and with his last breath attempted to use a Masonic distress signal to prevent his death. See details here.

If this really interests you, Quinn's book The Mormon Hierarchy : Origins of Power contains a lot more citations and historical evidences.