A couple more thoughts.

The song does not sound like a conventional pop song. Thus Tin Pan Alley origin seems unlikely. The girl isn't even named -- as are the heroines of most such songs: Fabiola, Anona, Cherokee Rose, Snow Deer, Blue Feather, Rainbow, Seminola, Singing Bird, Starlight, My Little Indian Napanee, Moon-Bird, Golden Arrow, Iola, Lo-Na, Falling Leaf, Towanda, Watseeka et al. (OK, I admit it, I've been collecting them for years.)

It could be a newspaper or magazine poem set to music or something of the kind. But it sounds too modern to be placed among older songs (1840s-90s) like "Blue Juniata," "The Sachem's Daughter," "Minnehaha," etc.

What tickles the imagination is that there could be something quasi-historical in this. The mention of the lover in prison is an odd note that hints at somebody's life story. It is nearly unheard-of, in the first half of the 20th century, for prison and Indian love motifs to appear together in a song.

Re the "Bright Mohawk/Red River Valley" question, though the scansion is similar, the tune is nothing like Red River Valley. I doubt any connection.   

Bob