Source:John Whitmer handled the plates - "Theodore Turley's Memorandums"

Turley claimed that John Whitmer said: "I now say I handled those plates. there was fine engravings on both sides. I handled them...and they were shown to me by a supernatural power."

Turley claimed that John Whitmer said: "I now say I handled those plates. there was fine engravings on both sides. I handled them...and they were shown to me by a supernatural power."

Theodore Turley claimed that John Whitmer said:

[Theodore] Turley said, ‘Gentlemen, I presume there are men here who have heard [John] Corrill say, that Mormonism was true, that Joseph Smith was a prophet, and inspired of God. I now call upon you, John Whitmer: you say Corrill is a moral and a good man; do you believe him when he says the Book of Mormon is true, or when he says it is not true? There are many things published that they say are true, and again turn around and say they are false.’ Whitmer asked, ‘Do you hint at me?’ Turley replied, ‘If the cap fits you, wear it; all I know is that you have published to the world that an angel did present those plates to Joseph Smith.’ Whitmer replied: ‘I now say, I handled those plates; there were fine engravings on both sides. I handled them;’ and he described how they were hung [on rings], and [said] ‘they were shown to me by a supernatural power;’ he acknowledged all.

So, the apostate Whitmer insists that he physically handled the plates, and attests to having seen fine engraving "on both sides." Even when apostate, he would not deny what he had seen, but had to claim that he couldn't know if the translation was accurate, since he had no witness of that.