What can I do if I am falsely accused of stealing?
If you are under investigation for stealing, do not speak to anyone, especially the police, at your home, work, or other venue, without having an attorney present. Police have been trained to get you to say incriminating or inconsistent statements, which can be held against you in a court of law.
When you are accused of theft--or any crime--the very first thing you should do is NOT TALK. Do NOT say anything about it to anyone, especially the police. As an old saying from police TV shows goes, "Anything you say can and will be used against you."
Obviously, anything you say to the authorities (police, prosecutor, etc.) can be used against you. But if you say anything to anyone else and that statement comes to the attention of the authorities, they may be able to use that, too. Even if you think you're only saying things that favor you--defenses, excuses, alibis, etc.--if you later contradict something you said earlier, the authorities can use that contradiction to "impeach," or damage, your credibility. You have the right to not say anything: it is your 5th Amendment right to not incriminate yourself (your right against "self-incrimination"), commonly called the "right to silence" or "taking the 5th." Exercise that right.
(When we say do not say anything about the case, it goes without saying that you should NOT post anything on social media about your case!)
Second, retain an attorney. While the penalties you might face will vary with the amount of money or value of property you are accused of stealing--the more valuable, the longer the potential jail time--if you are charged with theft, prison is a possibility, as are fines. If convicted, you will have a theft conviction following you around and accessible to anyone (e.g., landlords or employers) who does a background check. There is a lot at stake. Therefore, you want to hire an experienced criminal defense attorney to represent you. Once you hire your attorney, follow his or her advice--you are hiring him or her for his or her expertise.
You also want to make things as easy as possible for your lawyer. Collect, collate, and copy any documentation that might exonerate you, such as by showing that you could not have committed the crime. For example, say you were at work when the crime was committed--make copies of time sheets. Say you were at a restaurant--do you have a bill or receipt? Say you had driven someplace else--do you have any toll receipts showing where you went?
Also, make note of any other evidence or testimony that may defend you, which your attorney can request in the proper way. For example, if you went to any stores that had security cameras at the time of the alleged theft, let your lawyer know. The attorney can subpoena the video footage. If you interacted with anyone while the theft was supposedly going on, your lawyer can speak to those potential witnesses, to see if what they have to say would help you. (And what your attorney says for you cannot be used against you the same way your own statements can; let your lawyer do the talking for you.)
Other actions you might take will depend on the circumstances of the alleged theft. For example, if accused of stealing from your employer, if the office has security cameras, your lawyer will likely look to get that footage, to see what it shows.