What's your question? Either way, the answer is to hire an appellate attorney to look into this if he/you have been convicted.
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The prosecution is not required to record witness statements. but it is a good idea so the jurors can determine for themselves what was said. In terms of evidence, the jury can believe one witness over several but the evidence must be sufficient to prove beyond a reasonable doubt the guilt of the accused.
The simple answer to you question is, "no", they are not required to record witness or suspect interviews, although it is the best practice.
As to the rest of your statement, what you are describing is a case where you believe that someone, (yourself?) was wrongfully convicted. Under most circumstances, the best way to deal with that kind of a problem is to file an appeal. Ask the trial attorney to file an appeal, (you have 60 days from the day of sentencing) and request representation by Appellate Defenders.
Good luck with your case.