CHARLOTTE, N.C. — For five years, the death of Sandra Baker Joyner after a mini-facelift was attributed to medical error. But last month, investigators proposed a more sinister explanation.

As she lay bandaged in the recovery room, Joyner was poisoned by a nurse anesthetist who believed Joyner had stolen her boyfriend back in high school some 30 years ago, authorities say. The nurse anesthetist, Sally Jordan Hill, 50, is jailed without bail on first-degree murder charges. Yesterday, prosecutors announced they would not seek the death penalty.

Joyner, 45, had gone to the office of Dr. Peter Tucker in 2001 for a facelift, fat grafts to her lips, and laser therapy on her eyelids and facial scars. But she went into respiratory arrest in the recovery room and was taken to a hospital, where she died several days later after being taken off life support . An autopsy blamed her death on a lack of oxygen to the brain caused by respiratory arrest.

At a court hearing last month, Chuck Henson, a Charlotte-Mecklenburg detective, said he believes Ms. Hill poisoned the patient by injecting her with fentanyl, a powerful painkiller. The detective said he also believes Ms. Hill turned off an alarm that could have alerted other nurses to the patient’s condition.

And he testified that two people — the plastic surgeon and a technician — recall hearing Ms. Hill say Joyner stole her high school boyfriend. That comment was said to have been made during Joyner’s initial visit to Dr. Tucker’s practice in 1999. In court last month, two weeks after Ms. Hill’s arrest, defense attorney Jean Lawson disputed the allegations.

“There is no evidence that Miss Hill knowingly, deliberately selected this person and killed her. The suggestion that this is the product of a 30-year grudge is outrageous,” Ms. Lawson said. Ms. Hill and Joyner were students at Olympic High School in Charlotte in the early 1970s. Joyner was a member of the Class of ’73; Ms. Hill graduated a year later. During a 2003 deposition given to the state medical board, Ms. Hill said she knew Joyner in junior high and high school.

“She was one of the judges of my cheerleading experience when I was in the eighth grade,” Ms. Hill testified. Asked whether they were friends, Ms. Hill said no, but “I would see her and her then-boyfriend.”

Joyner later married John Joyner; the two separated before her death. Police said John Joyner is not the boyfriend that Ms. Hill believed was stolen from her.