A judge will try next month to untangle an apparent immunity deal that prosecutors gave a defendant who was initially arrested in a 2006 Ventura murder case. The man later became a key prosecution witness and later was rearrested and charged in the case.

If Superior Court Judge Edward Brodie decides that murder suspect Peter Rodriguez was given immunity from prosecution for the January 2006 stabbing of John Orrantia, 28, of Ventura, Rodriguez could be set free.

Brodie, who described the murder case as having "many twists and turns," set a hearing on the immunity issue for Aug. 12.

Appearing frustrated at times, Brodie said at a hearing Tuesday that he could only guess what prosecutors promised Rodriguez in exchange for his cooperation and testimony against co-defendant Gustavio Tapia.

"What is the scope of that immunity, I do not know. Everybody wants me to make a decision based on nothing," he said. "There are many kinds of immunity. The people (prosecutors) have a burden to try and tell me what this immunity was."

On Tuesday, Brodie said he's presided over many cases, and this was the first where immunity was given but no written agreement exists.

Rodriguez's attorney, Martin Zaehringer, told the judge that he wants charges against Rodriguez dismissed.

But Tapia's lawyer, Ron Bamieh, contends his client is not guilty and that it was Tapia's longtime friend, Rodriguez, who fatally stabbed Orrantia on Jan. 15, 2006. His brother, Orlando Orrantia, was wounded in the attack.

Charges against Rodriguez were dropped. He was rearrested in March, county records indicate.

Senior Deputy District Attorney Stacy Ratner told the judge that Rodriguez initially claimed to be 10 feet away from the stabbing and was a witness. After he was cross-examined at the preliminary hearing, prosecutors began to doubt his testimony, Ratner said.

After Rodriguez testified against Tapia, prosecutors moved him and his family to San Diego under a witness protection program.

At a hearing this year, Ratner gave Bamieh a copy of an agreement that did not contain any signatures. In the agreement, Rodriguez was given immunity from prosecution for assault with a deadly weapon, according to Ratner.