Dear Sasihr06,
There is no foolproof method of eliminating such incidents; these are the result of desperate, helpless, or unethical minds, depending on the situation. Understand the real situation behind why a candidate faked such documents. There are many possibilities.
A candidate may be a genuine person. Sometimes company management can be nasty and may not issue a relieving letter. Due to this, out of desperation or helplessness, candidates may resort to creating fake letters. As long as they can establish the work experience tenure with other authentic supporting documents, you may consider them. However, this also depends on your company policy. I'm just suggesting.
During the screening process, inform the candidate that any falsified documents will be discovered during reference checks. This can lead to legal action, immediate dismissal, and blacklisting. Hopefully, this should deter unethical behavior.
Maintain a checklist of standard documents and ensure you collect them before an offer is given. Complete necessary reference checks as the interview process is ongoing.
You can also request the candidate to submit a salary certificate (including details of employment) from the current employer. The candidate can approach the HR or accounting department to obtain the salary certificate, which should mention the employment tenure, job title, and monthly salary package. The candidate can give an excuse for loan purposes, etc. A genuine candidate would be willing to provide this document.
I hope this was helpful.