Wizard,
It is indeed a Gecko - a Banded Gecko, I think. They are found throughout the Mojave Desert, even out my way near 29 Palms. Geckos are nocturnal creatures, and the only North American lizard I know of that has a voice. Geckos will "squeak" during territorial scuffles with other geckoes, or when they are terrified.
It does look like he had a recent close call with some predator. Good survival strategy; leave the back part flopping to distract the assailant while the front part exits "stage right" ;-)
Are you planning to return him to where he came from? His survival chances will be best there.