Kevin David Cuillard, 41, was taken into custody without incident, said Sandy police Sgt. Jon Arnold.
On Friday, Cuillard was being held without bail at the Salt Lake County jail on suspicion of first-degree felony murder.
Christensen had moved in with her granddaughter sometime during the past year due to health problems, Arnold said. She previously lived in Mt. Pleasant.
Cuillard's wife told police that her husband came out of the garage of their home holding a golf club and "walking with a purpose" toward the victim's bedroom, according to a probable cause statement filed with the jail.
The wife described Cuillard's face as being "very intense," as she followed him along and asked him what he was doing, according to the jail document.
Cuillard continued to the bedroom, where he closed the door, preventing his wife from entering.
The wife then called 911, and also told her two juvenile children to flee the home.
When the wife returned to the bedroom, she found her husband kneeling over the victim's unmoving body, and it appeared that he was strangling her, according to the jail document. The wife then fled the scene, police reported.
When Sandy officers arrived, they observed that Christensen, who was dead, appeared to have been bludgeoned about the head.
Cuillard was still in the bedroom and had obvious bloodstains on his clothing. The golf club, with the head no longer attached, was found on the bed, the jail document states.
During an interview with police, Cuillard admitted the blood on his clothing was "grandma's" blood, according to the jail documents.
Cuillard told police that "he had to do what he did to make things better," according to the jail document. "In his mind, had he not done it, things would have been worse."
Cuillard refused to elaborate on what he meant, according to the jail document.
Arnold said that Cuillard's wife reported that he had stopped sleeping in recent days.
Cuillard reportedly works as an information technology specialist for a Salt Lake County business.
In more than a decade, the only history of police calls to that address is two reports of a barking dog, Arnold said.
Laura Reese, neighbor who has known the Cuillard family for nearly eight years, told The Tribune: "They are very close friends and we love them and I couldn't be more shocked. ... I couldn't say anything bad, they're really good people."
Resse called Kevin Cuillard "a great guy."
"It just shows you that mental health is something you have to … be careful," she said.
Tribune reporter Taylor Anderson contributed to this story.