Nearly six years later, questions remain: Who killed the child? And why?
On Tuesday, prosecutors kicked off a three-week trial with evidence and testimony they hope will convince a jury that Esar Met, a Burmese refugee who had befriended the little girl, is the one to blame.
Met, 27, is charged in 3rd District Court with first-degree felony counts of child kidnapping and aggravated murder for the slaying of Hser Ner Moo. If convicted, he could spend the rest of his life behind bars.
As the prosecution and Met's defense attorneys made opening statements, the defendant leaned forward in his seat and furrowed his brow, eyes darting back and forth between lawyers and a Burmese interpreter expressively translating every word:
"On March 31, 2008, Hser Ner Moo was healthy and happy. She was excited for life and she went out to play never to return," prosecutor Matthew Janzen told the jury.
The next day, police found her body.
"She was no longer happy and healthy," Janzen said. "She had been sexually and physically abused. The life was beaten out of her."
But defense attorneys told jurors that no evidence proved Met was the killer.
There were no eyewitnesses who saw him abduct or slay the girl. And at no point while Met was questioned and detained, said defense attorney Michael Peterson, did he behave like a guilty person.
The DNA collected from Met's jacket and from under the girl's fingernails that prosecutors would blame on a violent struggle was actually the result of games and play from days before, added Peterson.
Met and Hser Ner Moo played together in the apartment complex where they both lived.
Once, Peterson said, Met cooked the girl and "her little friends" dinner. He would take her on bicycle rides and carry her around on his back.
"Esar Met loved the kids in this complex," Peterson told the jury. "Hser Ner Moo enjoyed this play. It made her happy. She was never upset at all by any of this activity with Mr. Met. There is no evidence that Mr. Met mistreated her. Ever."
But it was this playfulness, prosecutors said, that allowed Met to get close to the girl he allegedly would kidnap, and then rape and murder inside his basement apartment.
Hser Ner Moo's disappearance prompted hundreds of volunteers to search for her. Police said she was recognized throughout the community, though no one had seen her that day.
The child's family lived in the same complex and was friendly with several of the men who lived in Met's apartment, including at least one roommate who had been approached by Hser Ner Moo's father on the day the girl disappeared.
"The father came to their door asking, 'Have you seen my little girl? I'm looking for my little girl,' " Peterson told the jury. "[The men] say, 'No, we haven't seen her.' But then what do the roommates then do? Knowing that this gentleman is looking for his little girl, do they call out to the basement to see if Esar might be down there? To see if he had seen Hser Ner Moo? No."
This indifference, defense attorneys said, was unusual.
Peterson went on to imply that it was one of these men the four roommates with whom Esar Met had been assigned to live when he entered this country as a refugee just one month before the slaying who may be responsible for Hser Ner Moo's disappearance and death.
Met, who had been living in a Burmese refugee camp in Thailand, moved into the apartment about a month before the slaying. The other men had lived there much longer.
Hser Ner Moo's family came to Utah in August 2007 from the same refugee camp.
Officers who responded to the concerned family's home said they immediately had a "bad feeling" about the case.
"Call it a gut feeling, call it a mother's reaction it was just immediate," said former South Salt Lake police officer Jacob Burton, as he wiped his eyes and tried to steady his voice. "This wasn't a normal missing child who hadn't returned from school or had wandered to a friend's house."
On April 1, 2008, the girl was found face down in Met's shower, still in the pink shirt, pink skirt and pink coat she had worn the day before. Her shoes, photos shown in court revealed, were strewn across the room one in the toilet and the other on the tile floor.
"Evidence will prove beyond a reasonable doubt that Esar Met killed Hser Ner Moo after he sexually assaulted her and detained her," Janzen told the jury. "The four men who lived with him, his roommates, were absolutely surprised there was blood and the body of a child in their basement. They had no idea."
But defense attorneys painted a picture of Met's relationship with his four roommates as cold stemming from their being from different ethnic groups.
The roommates were arrested on April 1, 2008, but later released.
Police said at the time that the four men were not home when the girl was killed and did not know her body was in Met's basement bathroom.
Met was arrested at about 10 p.m. on April 1, 2008, at his aunt's Cottonwood Heights home. The aunt, Mi Cho, told police her nephew had arrived the previous day at about 3:30 or 4 p.m., and had spent the night on the floor, according to charging documents.
Burton, who aided in Met's arrest, said he did not try to hide or run from officers.
Eleven jurors comprised of five men and six women were chosen Monday to hear the three-week-long trial.
Just hours into the first day, prosecutors presented a graphic photo of Hser Ner Moo's body in the tub where she was found.
Her limbs bent at odd angles, the child lay in her own blood.
FBI Agent James Lamadrid said he called out to her to see if she was alive: "Hser Ner Moo? The FBI is here."
Police have said the girl was likely dead within an hour of leaving her family's nearby apartment.
South Salt Lake firefighter and paramedic Andrew Maurer, who responded to the apartment on April 1, 2008, testified that Met's basement "looked like a horror scene."
His supervisor, Captain Paramedic Paul Resmussen, testified that "for such a small girl, there was a lot of blood all over."
Met has pleaded not guilty to the charges against him.
This week's trial is the culmination of years of proceedings that included concerns over the defendant's mental competence and ability to understand the criminal proceedings.
Last month, Senior Judge Judith Atherton denied defense attorneys' request to suppress evidence found in Met's basement apartment that they said was searched illegally, without his consent.
On Wednesday, the child's parents and two brothers were expected to take the witness stand.
They did not attend Tuesday's proceedings.
A Missing Peace
Reporter Julia Lyon traveled to Thailand to trace the journeys of Hser Ner Moo and Esar Met from the Mae La refugee camp to Salt Lake City. Her series, reported in collaboration with the International Reporting Project, also explored the challenges their families and other refugees face in America. See the series at http://extras.sltrib.com/thailand.