He rode out of vision into legend. From Time Into Timelessness. Excellent documentary.

https://www.pbs.org/wgbh/americanexperience/films/billy/#transcript

Billy was always looking for a family. He wanted a home and that's the one thing that he never really had and couldn't get. I think he felt that Fort Sumner was home. Escape was one of his talents. As he rides out of view he passes into legend. Bill the Kid was considered a copkiller, that made him a hero.

Another excellent biography:
http://www.timkellerphotography.com/timkellerarts/WritingChasingBilly.html

N. Scott Momaday, from The Ancient Child:

The wound gaped open;
it was remarkably like the wedge of an orange
when it is split, spurting.
He wanted to close the wound with a kiss,
to graft his mouth to the warm, wet tissue.
He kept about the wound, waiting
and deeply disturbed,
his fascination
like the inside of the wound itself,
deep, as deep almost as the life principle,
the irresistible force of being.
The force lay there in the rupture of the flesh,
there in the centre of the wound.

Had he been born G-d,
he should himself have inflicted the wound,
and he should have taken the wound gently,
gently in his hands, and placed it
among the most brilliant wildflowers
in the meadows of the mountains.

He finds a fossil fish
there in the riverbed.
He wonders about it,
it is a long time dead.

The dish descends in rock,
as if the sheer incline
might slants its destiny
according to some sign.

So Sagittarius
must swim against the tide.
He reckons upon time,
and time is on his side.

His legend is secure,
he bodies resistance.
The fossil is himself,
his own indifference.

He wanders the high desert
like a coyote. The wind burns him.