Morgan Mengel, 36, was on trial for the June, 2010 death of her husband, Kevin. Authorities say she goaded 22-year-old Stephen Shappell into beating Kevin Mengel to death with a shovel then burying his body.
However, in court on Friday, a judge ruled the jury was 'unavoidably tainted' after a West Goshen police officer described, during testimony, a conversation with Mengel's father in which he said his daughter 'could be despicable.'
The judge ruled the statement as inadmissible, but later said he saw way for the jury to completely disregard it.
Morgan Mengel's attorney has said Shappell acted of his own accord. Shappell pleaded guilty and was expected to testify for the prosecution.
No date was immediately set for the retrial.