I'm a defendant in a civil lawsuit . The plaintiff has filed a verified complaint for Replevin, Civil Theft, and conversion.

A polygraph is not admissible in court. The rules of evidence generally require witnesses to appear in person, but there are limited (and complicated) exceptions. A judgment in a lawsuit cannot be collected from your spouse unless he has money or assets owed to you. If the outcome of the case is important to you, you really need an attorney.

These are serious claims and you need an attorney. Letters and polygraphs are not useful in the least. Either you have a defense, or you lose and will owe up to three times the amount claimed (civil theft).

As stated, polygraph is useless and inadmissible. Letter can't help, you need to call the people who would write the letters to testify.

These sound like serious claims, and Replevin actions can move through the courts relatively quickly. The claims can carry pretty serious consequences. You should definitely consult an attorney on these issues and to represent you in the case.