In an attempt to stave off his June 24 execution, condemned murderer Ronald Watson Lafferty filed a petition for a writ of habeas corpus Wednesday in U.S. District Court.

Lawyers Michael D. Esplin and Gary H. Weight, Provo, filed the petition. The case was assigned to U.S. District Judge J. Thomas Greene.The basic contention of the petition is that Lafferty was not mentally competent to assist his lawyer, Richard Johnson, in the trial.

"There were things that happened at the trial that would indicate he did not effectually assist," Weight said.

Esplin said Lafferty refused to allow Johnson to establish an insanity defense.

There is no question that he was mentally ill, as the court made that ruling, Esplin said. The question is whether Lafferty could materially assist his lawyer.

"Constitutionally, you're denied the right to a fair trial if you are not competent to proceed," he said.

In addition to the writ, the lawyers filed a motion for a stay of Lafferty's scheduled execution. Esplin said he believes "the judge will have to grant that motion."

Having changed his mind, Lafferty now wants to fight the execution. Another issue is that the judge refused to allow certain evidence to be entered by the defense.

Lafferty was convicted in the July 24, 1984, murder of his sister-in-law, Brenda Lafferty, and her daughter, Erica. His brother, Dan, was convicted of the same crimes but was sentenced to life in prison.