The Maricopa County Sheriff's office said the woman lived with her son and his girlfriend at the girlfriend's condo. She confronted him on Monday morning with two pistols that she hid in her robe, according to police.
Court records show she believed her son, Thomas Blessing, and his girlfriend were talking about putting her in an assisted living facility because she had become "difficult to deal with".
Blessing then pointed the weapon at her son's girlfriend.
"You ended my life, so I'm taking yours", Blessing allegedly said during her arrest, the Arizona Republic reported.
The son died from two bullet wounds to his neck and to his jaw. But she still had the second one. And later the police arrived and took her into custody.
Police were able to arrest Blessing without further incident, and when asked what should happen to her, she reportedly said she should be "put to sleep", according to court records, and also said she had meant to kill herself but did not have enough guns.
Blessing also told police that she had also meant to kill herself, according to court document.
The sheriff's office said they are investigating the case as a domestic violence homicide.
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Blessing faces charges of murder, aggravated assault and kidnapping after her son's death, according to police.
Watch her first court appearance here.
Blessing's next court hearing is scheduled for 8:30 a.m. July 10.
When describing the tragic murder, a police officer at the scene said. She also said she should be "put to sleep" for her actions.
Her bond was set at $500,000.
The incident, which police described as "a freakish turn of events", took place at the home she shared with her son and his girlfriend in Fountain Hills, Arizona.
Blessing's husband, Billy Blessing, died in 2007 in Florida, according to an obituary in the Orlando Sentinel.