I have a dui case. The officer just resigned for altering the dui test. Can the case be thrown out.

It's probably not quite as simple as having the case "thrown out."  However, you are likely in a very good place to either have the case dismissed or, if necessary, to win in court.  One of the key concerns I have is how many officers were involved in your arrest?  Was there more than one officer on the scene when you were pulled over?  If you were tested after your arrest for alcohol (via your blood, breath or urine), was there a separate officer who administered that test? The officer who arrested you is very likely the State's primary (if not only) witness in the case against you.  If the officer resigned, that means he is no longer getting paid.  If he is not getting paid, it is extraordinarily unlikely that he will come to court to testify.  If he does show up, and he is no longer a police officer, that simple fact will make him less credible to the jury.  Further, if he did indeed resign over having altered test results, that seriously calls his credibility into question.  The prosecutor knows this, and will likely not want to try the case because of it.   While the resolution to your case depends on a multitude of facts specific to your particular situation, the limited amount of information you provided leads me to believe that this can be resolved in your favor and without a trial.      

The officer's credibility is at issue in this case.  It is important that you have an attorney who is versed in DUI law to properly fight for you.  Getting your case dismissed is not automatic in this situation.