(CNN) -- A Florida jury has recommended the death penalty for a plumber who kidnapped, raped and murdered a police detective's daughter.

Denise Lee's frantic 911 call was the centerpiece of her killer's trial.

Michael King, 38, showed no reaction Friday afternoon as the jury's 12-0 decision was announced in Sarasota. Jurors deliberated for nearly three hours.

King was convicted a week ago of first-degree murder and related offenses in the January 17, 2008, death of Denise Lee, a 21-year-old mother of two boys.

Nathan Lee and Sgt. Dave Goff, the victim's husband and father, remained composed in court. They had maintained a daily presence in the courtroom during a trial that included the heartbreaking tape of Denise Lee's frantic 911 call on her captor's cell phone. Watch the jury recommend death »

In Florida, a jury's recommendation for a death sentence is advisory. King will be formally sentenced later. Judges rarely overturn a jury's unanimous decision.

Jurors Marcia Burns and Pat O'Quinn told reporters that defense testimony about King's head injury from a sledding accident and his low IQ carried little weight in the jury room.

Denise Lee's father and husband had hoped for the death penalty. "I don't think he should be able to live another day," Nathan Lee said Friday as he awaited the verdict.

Lee and Goff told the jury that she was a bright young woman who put aside her career ambitions to marry her college sweetheart and raise their two boys, now 2 and 3.

"She was everything we could wish for in a daughter and more," Goff said.

Several jurors had tears in their eyes as Nathan Lee described his wife as a devoted mother who was nursing one son and potty-training another when a stranger abducted her from their home.

Don't Miss In Session: Detective's daughter murdered

In Session: Detective's daughter murdered Trials on demand

"I was so proud to call her my wife," he said. "Denise was the love of my life, my soul mate. I knew after our first date that I had found the perfect girl."

He added that their boys "know their beautiful, courageous mommy has gone to heaven and now is an angel."

King's siblings spoke of how a childhood sledding accident left him with a head injury that contributed to a lifetime of troubles. One expert described the injury as a "divot" in his brain.

Experts testified that scans indicated that King's brain was abnormally shaped, especially his frontal lobe: the center for logic, planning and reason. His IQ was described as about 76, in the low range. A person with an IQ of 70 is considered to be mentally retarded, according to testimony.

King's brother, Greg, testified that the defendant was 6 when he crashed head-first into a post while being pulled on a sled by a snowmobile. "I felt bad for him," Greg King said. "I felt responsible, but I wasn't."

As a child, Michael King would get a faraway look in his eyes, witnesses said. Once, he fired his BB gun at witches he said he saw in the trees. Another time, he chased family members around the house with a running chainsaw. His eyes were "bugging out," his brother testified.

King also complained of headaches and hearing "a buzzing sound" in his head, Greg King told the jury.

King seemed to be deteriorating mentally in late 2007, according to testimony. He faced foreclosure, was considering filing for bankruptcy and broke up with a girlfriend on Thanksgiving Day. The ex-girlfriend, Jennifer Robb, testified that he sat on the bed staring into space and unable to dress himself.

"He acted as if he were somewhere else," she said. But she said she never knew him to be violent.

According to testimony, Lee was taken from her home during the afternoon, driven to King's home, sexually assaulted and then shot in the head and buried in a ditch.

During the trial, Lee's voice filled the courtroom as her desperate 911 call was played to the jury. Listen to the heartbreaking 911 call »

A 911 operator repeatedly said "Hello," and Lee was heard pleading with her captor: "I'm sorry. I just want to see my family. ... I just want to see my family again. Please. ... Oh, please, I just want to see my family again. Let me go."

Eventually, Lee managed to say, "My name is Denise. I'm married to a beautiful husband, and I just want to see my kids again. ... Please, God, please protect me."

Lee's heart-shaped ring, a gift from her husband, was found in King's car, and hair matching hers was found on duct tape at King's house.

According to testimony and court records, Lee fought frantically for her life, banging on the windows of King's green Camaro, screaming for help and begging one witness, "Call the cops."

Several people reported seeing something suspicious and called 911. But authorities didn't find Lee in time, and allegations that dispatchers mishandled the calls have led to criticism of the local 911 system.

The 911 communications breakdown was blamed on a shift change, and two dispatchers were suspended, according to the St. Petersburg Times.

Lee's husband has launched a foundation bearing her name that works toward 911 reform. He plans to file a lawsuit this month, a family spokesman said.

All About Capital Punishment • Murder and Homicide • Criminal Trials