A Missouri prison nurse fatally poisoned her husband with antifreeze, according to police, and then allegedly set their home ablaze to hide the evidence as part of a plan to marry a convicted killer serving a life sentence in prison.

Authorities arrested Amy Murray, 40, on Thursday and charged her with first-degree murder and armed criminal action after she allegedly set her home in Iberia, Missouri, on fire with the body of her husband, Joshua Murray, inside on December 11, 2018, ABC News reported.

After the fire began, Amy Murray took her 11-year-old son and the family dogs to a McDonald’s, according to a probable cause statement obtained by KQFX.

She was allegedly having an affair with Eugene Claypool, an inmate at Jefferson City Correctional Center, where she worked as a nurse, at the time of the blaze.

Claypool has been serving a life sentence at the prison after he was convicted of fatally stabbing a 72-year-old man who won $1.7 million in the lottery.

Amy Murray recorded her phone conversations with Claypool, telling him she lost interest in staying married to her husband, according to court documents obtained by KQFX.

She even reportedly told the inmate she could marry him because her husband was “out of the picture,” and she spoke about hiring an attorney to fight for Claypool’s early release, according to the court documents.

Fire marshals investigating the incident found the blaze began in the home’s master bedroom, and the person who started the fire used an accelerant to set the home ablaze, according to the Miller County Sheriff’s Office.

A medical examiner’s autopsy determined that Joshua Murray had died from antifreeze poisoning before the inferno destroyed the home.

Amy Murray was booked into the Miller County Adult Detention Center on $750,000 bond.