The Gilbert Haynes you're looking for was my GG grandfather, b. 3 Jun 1859 in Orange Co. TX, m. Martha Miriam Womack 18 Mar 1880 in Orange Co. TX, d. 2 May 1896. Their children were George Jeptha, Henry Presley (or Preston) "Press", Jesse Phelps "JP", and Mary Octavine. I have a good bit of information on this line if you're interested.
Do you have any more information about Gilbert's death while on posse?