Blood Splatter Expert Supports Ex-Pastor's Claim That He Didn't Kill Wife

"If the defense thinks that the prosecution has put on a pretty compelling and tough case, they may feel they have to put him on the stand, but if they think that they've still got a really solid shot of an acquittal or a hung jury without him testifying, they'll probably try to keep him off the stand," Abrams said.

It wasn't until a grisly suicide in 2010 inside Schirmer's office that authorities decided to revisit the case of Betty Schirmer's death and arrest the pastor.

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The man who broke in and shot himself in Arthur Schirmer's office at the Reeders United Methodist Church, Joseph Mustante, was the husband of the pastor's secretary, Cynthia Mustante, Poconos Township Police Detective James Wagner said.

Mustante's suicide was prompted by the discovery that his wife and the pastor had apparently been having an affair, Wagner said.

On Dec. 11, 2012 -- more than 13 years after Jewel Schirmer died, a Lebanon County judge ruled Arthur Schirmer would be tried for her murder.

ABC News' Emily Friedman and Alyssa Newcomb contributed to this report