CHICAGO (CBS) — A DePaul University Legal Analyst is giving Drew Peterson only a slim chance for reversal of his murder conviction.

Jurors convicted the former Bolingbrook police sergeant of murdering his third wife, Kathleen Savio.

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But Peterson now argues that only happened because of mistakes by his attorney Joel Brodsky which let in hearsay testimony which encouraged jurors to convict.

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Professor Leonard Cavise at DePaul says Brodsky made a mistake, but doubts that will help Peterson much.

“I think it is going to be very, very hard to prove that the mistakes that he made would have changed the outcome to the satisfaction of the trial judge,” said Cavise.

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Cavise says Peterson would have a better chance in appellate court but isn’t likely to get a new trial from his judge in Will County.