We don't know if you failed to join a union or if your employer would not recognize your union to represent you. Lots of good advice is being given here, please heed it. Your work colleagues probably know that you were suspended/sacked. It's not unthinkable they believe you are in the wrong. If you do nothing on your own behalf, it's tantamount to guilt in the eyes of many. Your reputation has been tarnished greater than you think and there may be repercussions for your future. The gardaí become involved, there is a court case, you're found guilty or not guilty, newspapers print news and anything of human interest stories (like yours) sell papers.
You must have financial resources to fight the allegations against you. If you haven't resources, you are facing an uphill battle. Word-of-mouth is a dangerous weapon when used against you. At this moment your employer holds all the aces and you are shuffling deuces and trays. Look at it this way:- Would you employ somebody who robbed his employer? Through your inaction and naivité, this is where you stand.
In your favour it's widely known that passwords are usually commonly known by other work colleagues. In the absence of cctv your case is more difficult to assess. We have your word. Your employer will be well aware of what must be done and can offset his/her legal fees against profits.
Anybody looking in on this thread might like to consider their vulnerability if they are not members of a trade union.