LITTLE ROCK, Arkansas — Family members of the victims of an inmate scheduled to be put to death next week asked a federal judge to delay his execution Tuesday, saying the coronavirus pandemic puts them at risk if they travel to attend it.

The family members of Daniel Lewis Lee’s victims asked that Lee’s execution be put off until a treatment or a vaccine is available for the virus. Lee, convicted of killing an Arkansas family as part of a plot to establish a whites-only nation in the Pacific Northwest, is scheduled to be executed on July 13.

Lee is scheduled to be the first federal inmate executed in 17 years. Lee, 47, was convicted of the 1996 murders of gun dealer William Mueller, his wife, Nancy, and her 8-year-old daughter, Sarah Powell.

The request to halt the trial was filed by Earlene Peterson, Nancy Mueller’s mother and Sarah’s grandmother; Kimma Gurel, who is Nancy Mueller’s sister and Sarah’s aunt; and Monica Veillette, who is Nancy Mueller’s niece and Sarah’s cousin. Peterson lives in Arkansas, while Gurel and Veillette live in Washington.

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The three have opposed Lee’s execution, but have said they wish to exercise their right to witness it. In the filing, the three say the federal government is putting them in the untenable position of risking their lives by traveling to Indiana for the execution while coronavirus cases surge nationwide.

“At each stage of these proceedings and their travel to participate in them, plaintiffs face grim risks of exposure to COVID-19, a disease which for these vulnerable plaintiffs, could prove lethal,” the filing said.

The three asked to join a lawsuit seeking to halt the execution of another inmate scheduled to be executed two days after Lee. A Zen Buddhist priest who is the spiritual adviser for that inmate has made similar arguments about the execution moving forward during the pandemic. A Catholic priest and a spiritual adviser for a third inmate, scheduled to be executed July 17, also asked Tuesday to intervene in the case.

Lee’s attorneys last week filed a separate motion before a federal judge in Arkansas to delay his execution, also citing concerns about the virus.