An elderly Las Vegas couple was found dead by park officials at the Death Valley National Park after a murder-suicide.

Officers in Inyo County responded to a 911 call from a man, identified as 73-year-old Paul Fischer, according to a press statement by the National Park Service.

Fischer confessed to the 911 operator that he had killed his 72-year-old wife, Mary Fischer. He then told the operator that he was going to kill himself and gave the operator directions about where to find their bodies.

Responding officers found the couple dead when they got to the scene. They found a note inside the couple’s car written by Paul Fischer explaining that his wife suffered from chronic health conditions.

According to the FBI, one of the leading causes of domestic murder-suicides is one person’s desire to relieve the other person of a disability or illness. Most victims of such incidents are children and elderly adults.

Advocates for disability rights argue that when domestic murder-suicides are framed as “mercy killings,” it dehumanizes the person with a disability while romanticizing the perpetrator’s actions.

Two common features of domestic murder-suicides are that adult white males commit an overwhelming number of them, and that guns are the most common weapons used to commit the murders.

Death Valley National Park is about 3.4 million acres and reaches across the California-Nevada border. With the park’s harsh conditions and temperatures, most deaths are due to medical events, car accidents, suicide, or heat exposure.