Lorenzo Saunders to Thomas Gregg (January 28, 1885): “Smith and Rigdon had an intimacy but it was very secret and still and there was a mediator between them and that was Cowdery. The [Spalding] manuscript was stolen by Rigdon and modelled over by him and then handed over to Cowdery and he copied them and Smith sat behind the curtain and handed them out to Cowdery and as fast as Cowdery copied them, they was handed over to Martin Harris and he took them to Egbert Granden [sic], the one who printed them, and Gilbert set the type.” Pages 132-133.in True Origin of the Book of Mormon (1914) by Charles Shook.
Cowdery was excommunicated in 1838. In his response to the excommunication, he wrote: ‘I will not be influenced, governed, or controlled in my temporal interests by any ecclesiastical authority or pretended revelation whatever, contrary to my own judgement.’
Former Mormon apostle William McLellin, who left the church and later wrote against it, once remarked that Oliver Cowdery would bear strong testimony of the Book of Mormon when amongst the saints, but when he was half-drunk, he would admit that it was all “a bottle of smoke.”