By 1863 Michael Dyer was back in Nashville with his family. His daughter Sarah Claire "Sadie" Dyer (my great-great-grandmother) was born there on 8 October 1863. In January 1866, he left Nashville. His wife Mary placed a "Missing Friends" advertisement in the Boston Pilot on 6 October 1866. This advertisement provided me with the information about his county of birth. He eventually returned to Nashville; his son Michael J. Dyer was born about 1868, and he is listed in the 1869 Nashville city directory. He ran a saloon on S. Market and also worked as a blacksmith.
On 3 June 1870, Michael Dyer committed suicide. He had been drinking heavily, and he shot himself in the head. An account of his death in the Nashville Republican Banner, 5 June 1870, stated that "Dyer was known as a hard case and treated his family with great severity." However, I think it is worth noting that before he committed suicide, he drove his family to a neighbor's home. His family did not have to witness his suicide, or hear the gunshot. If they had, surely they would have been even more traumatized.
There was a coroner's inquest. I am hoping that the record of this inquest survives, but I have not yet been able to locate it.
An account of Michael Dyer's death is available online:
Nashville Union and American, 5 June 1870, image 4
Nashville Republican Banner, 5 June 1870, page 4