https://tpwd.texas.gov/regulations/outd ... er-speciesExotic Animals And Fowl
An exotic animal is any animal that is not indigenous to Texas, including but not limited to aoudad sheep, axis deer, elk, sika deer, fallow deer, red deer, and blackbuck and nilgai antelope. An exotic fowl is any avian species that is not indigenous to Texas and is also not protected by the federal Migratory Bird Treaty Act, including but not limited to ratites (emu, ostrich, rhea, cassowary, etc.).
It is UNLAWFUL to:
hunt an exotic without a valid hunting license (Class C misdemeanor);
hunt an exotic on a public road or right-of-way. (Class A misdemeanor);
hunt an exotic without the landowner's permission. (Class A misdemeanor); or
possess an exotic or the carcass of an exotic without the owner's consent (Class A misdemeanor).
However, the ear tags imply that this animal is owned by someone. If it were mine, I would be very unhappy to find out that someone killed it and i would do whatever I could to see that they were punished to the full extent of the law (whatever laws apply).
Personally, I would call the local Game Warden's office in that area and tell them where it has been seen. They may very likely have some information about where it came from and who is missing one of their elk. It could then be darted and returned to its owner.