2 Guilty in Plot to Kill Ex-Spouse : Crime: Federal jury convicts former Tustin woman and her present husband in failed murder scheme to collect $300,000 in life insurance.

A federal jury Thursday found a former Tustin woman and her husband guilty of plotting to kill her ex-husband in a scheme to collect $300,000 in life insurance.

Margo J. Thibault-Lemke and William Lemke, her boyfriend at the time of the incident, were each convicted of murder-for-hire, wire fraud and conspiracy.

Prosecutors had argued that the couple, both 41, hired four men in late 1987 and early 1988 to kill attorney Richard Thibault. The couple was hoping to collect on two life insurance policies totaling $300,000, prosecutors said.

Prosecutors said there were four different plans to murder Thibault, but all failed and Thibault was never harmed. Thibault-Lemke, who was married to Thibault at the time, later divorced him to marry Lemke.

The jury, which deliberated for three days on the case, came back split on several counts of murder-for-hire and fraud. But U.S. Assistant Atty. Elana S. Artson said the government will probably not seek to retry the defendants on those charges because they were found guilty on the majority of the 14-count federal indictment.

“The government is very pleased with the verdicts,” she said.

Defense attorneys could not be reached for comment late Thursday.

Throughout the trial, a bizarre account of the bungled murder scheme emerged as the four allegedly hired to kill Thibault testified about their involvement. The four men, including one who is the stepbrother of Thibault-Lemke, were granted immunity in exchange for their testimony.

Thibault-Lemke, who tearfully testified on her own behalf, said that she had no intention of killing her husband and was actually trying to thwart the plans of one of the alleged hired killers, who she said wanted to murder her husband in exchange for money for a sex-change operation.

She said she and her family members were threatened by David Lamb, whom they had known as a woman named Jan. Thibault-Lemke said she was trying to stall Lamb when she was arrested.

But Lamb, who lived in Devner at the time, told the jurors a different story. He said he went to law enforcement authorities with the murder plot after he thought Thibault-Lemke was reneging on her end of the deal. He said she had canceled a plane ticket that she had purchased for him so he could come out and commit the murder.

Lamb agreed to have authorities record a telephone call to Thibault-Lemke in January of 1988, during which they discussed a plan to poison Thibault with curare, a muscle relaxant derived from a South American plant that some natives use as poison on arrows.

During that conversation, Thibault-Lemke said that she was running low on cash and couldn’t afford Lamb’s plane ticket, but was still interested in buying the poison that she planned to apply on steering wheel of her then-husband’s car.

“I hope this works,” she said toward the end of the conversation.

Lemke denied any participation in a plot to kill Thibault. But the men alleged to have been hired to kill Thibault said that Lemke was actively involved in the schemes.