In WV(ive heard not proved) that you have to be feared for your life before use of a deadly weapon is advised.
Not the case in TX under this particular statute- see #11 and #3 above. (EDIT: also #16.)
Well can you at least hold him at gun point till the cops show up..
This question is at least as complex as the initial question, if not more so. I'll try and give you the short version.
First, threatening to use deadly force generally requires the same justifications as the actual use of deadly force. The penalties for improper threats of deadly force are likewise very similar. We are talking about serious jail time.
It
is legal in TX for someone to use deadly force (or threaten to use it- see above paragraph) to detain a criminal who is in the process of committing certain serious crimes. That said,
improper use of deadly force to detain someone against his or her will is a crime in and of itself- it's called kidnapping.
Before attempting to detain a suspect, you need to be sure that
it is absolutely obvious to any reasonable observer that there is a serious crime in progress. The underlined phrase is crucial; the crime must not only be obvious to you- it must be obvious to
any reasonable person observing the situation.
The crucial problem is that most burglaries, vehicle or otherwise, are generally less obvious and clear-cut than other crimes such as robbery, murder, or rape. Only a few seconds of astute observation may separate the innocent from the guilty. Can you be
certain that the man standing next to your car with the alarm going off was actually trying to steal the stereo seconds earlier? Would an impartial observer be likely to agree? Could the man have bumped the car by accident? Could he have tried the door handle thinking the car was his sister's, a similar dark-colored 4-door sedan parked a few spaces over? Will he forgive you for screaming obscenities at him and making him lie on the ground at gunpoint until the cops arrive, when all he was trying to do was bring in some groceries?
My opinion? Regardless of what Penal Code 9.42(3)(A) says, I will let the cops handle it.