Trial of Houston Lawyer Accused of Plotting to Kill Wife Is Delayed After New Evidence Surfaces About Former Mistress

April 12, 2012 — -- The trial of a man accused of trying to have his wife killed has been delayed after the disclosure of new information that the prosecution's star witness, a woman who confessed her involvement in the murder attempts, might have been involved in a prior murder-for-hire plot.

The revelation that Michelle Gaiser might have been involved in previous murder plots and other criminal activity caused the postponement of the solicitation of capital murder trial against Jeffrey Stern, a prominent Houston attorney who has been charged with masterminding three failed murder attempts on his wife, Yvonne Stern, 54.

Watch Chris Cuomo's interview with Yvonne Stern on the latest episode of "20/20."

Dick DeGuerin, a criminal defense attorney who has no connection to the case, said the new information about Gaiser was troubling.

"This is a startling revelation, and it severely damages the prosecution's case," DeGuerin said. "Their case relies on the believability of the Gaiser woman."

The trial, which was to have started on Friday, has been pushed back to July 27, according to the Houston Chronicle.

The prosecution said Gaiser, 39, ordered a hit on someone else before ordering hits on Stern, and allegedly put bleach in someone's drink, the Chronicle also reported.

Gaiser is Jeffrey Stern's former mistress, and she has pleaded guilty to arranging the attempts on Yvonne Stern's life. In exchange for her guilty plea and cooperation with the government, prosecutors agreed to reduce her possible life sentence to a maximum of 25 years in prison.

The prosecution contends that Jeffrey Stern, 55, is as guilty as his ex-mistress in the hits on his wife. He admitted the affair but denied any wrongdoing in the murder attempts.

The first alleged attempt to kill Yvonne Stern was a drive-by shooting at the couple's Houston home in February 2010. The house was sprayed with bullets, but Stern, who has two children, wasn't home.

Two months later, a man shot at her through the glass in the door but missed. The entire family was at home, but no one was hurt. The family moved to an apartment for safety after the second incident, but someone tracked Stern down there.

She was sitting in her car in the parking garage at the apartment in May 2010 when a man approached her window and shot her in the stomach. She played dead, then drove herself to a gas station to get help.

Yvonne Stern initially filed for divorce after learning of her husband's infidelity, but took him back. She has said she does not believe he was responsible for the attempts on her life.

The couple left a court appearance in November hand in hand. Yvonne Stern paused then to tell reporters that she loved her husband and had forgiven him for "his indiscretions."

"He had nothing to do with this and could not do anything with this," she said. "We are victims of a fatal attraction."

ABC News' Suzanne Yeo contributed to this report.