My Sisters Husband Threatened Her Saying I Hope You Die And If You Don't You Will Soon. I Promise. Any Suggestion?

Call the police. What he did is against the law. Make sure they fill out a report. Get a personal protection order against him - the police will tell you how to do it. Does this clown have any warrants out on him? The police can check that, too. Most of these guys are cowards but any threat he makes should be taken seriously and reported immediately. And I wouldn't worry about any of his badass friends, unless they are so stupid that they would risk the possibility of going to jail for this idiot.

I would take that as a legitimate threat on a persons life and is illegal.  Involve the police right away

First, report it to the cops.  It is a crime to make death threats.  If you can catch him on the phone doing so and get a recording of it, it will help a GREAT deal.  In any event, do whatever is required.  You can assess how serious the threat is better than us, and if it means she has to leave town or something, then have her do so.  Good luck. Will say a prayer for you and her.

Report this dog to the police dept... Any man threatens or beats a woman is less than man .This is a scare tactic to control her ,  then she should initiate restraining order and  if she is really scared   move to unknown location and keep restraining order in effect if he show up unnoticed  call police

I agree with everyone who said to Report It To The Police.  When she goes to get a divorce, she Needs that on Public Record for it to be admissible in court.  Then, take her to the nearest women's shelter, there, they can give her information on domestic abuse, and give her resources to safe houses, if need be.  She needs to get away from him ASAP!!!! (Believe me, I have been there).

Tell her to immediately leave and go to an abused woman's shelter, especially if she has children. They will protect her and her privacy, he will not be able to locate her and they will not give out any information. All threats should be taken seriously.  They can help her contact the people she needs to, to establish a protective order against him and other ways to keep herself safe. This is a form of mental abuse which can quickly lead to the real thing. Don't take it as an idle threat.

Firstly, try to get these threats recorded on tape first.  Record all phone conversations and any meetings.
 
Secondly, it's a no brainer.  Your sister needs protection.  By doing nothing will surely potentially leave her vulnerable to a very dangerous and exposed situation.  She can consult a criminal lawyer who could work with the police to help ascertain a new identification.  Any children here involved?  If so, the severity is surely heightened and the authorities must act on it.  She must not waste any time; act on it now or else it may be too late!