LEBANON - The third murder trial of Ryan Widmer in the bathtub-drowning of his wife of four months will differ significantly from his two previous trials.

"The third trial will be a different ballgame," says Mark Krumbein, a seasoned Cincinnati defense lawyer who has some experience as a prosecutor. "Already, this case is so different from other murder cases in so many ways."

Experts say it's rare for two mistrials to be declared in the same murder case.

Two big factors are game-changers for Warren County prosecutors and for Widmer, 30, of Mason, as his three-week trial starts Tuesday:

The prosecution's mystery witness, whose identity is being kept secret until just before his trial starts. The witness reportedly heard Widmer confess to the 2008 drowning of his wife, Sarah Widmer, 24, a Fort Thomas dental hygienist. But that person's identity is being kept secret under revamped Ohio court rules. The rules took effect July 1, a month after Widmer's second trial ended with a deadlocked jury.