A 7-year-old girl who disappeared from her Utah home Monday was likely dead before her parents realized she was missing, allegedly killed by a neighbor in the apartment complex where she lived, police said today.
"It [the killing] occurred within the hour, within an hour of her leaving her house," South Salt Lake Police Chief Chris Snyder said at a news conference today. He said the girl died "fairly quickly, probably before the family even knew she was missing."
Hser Nay Moo was found dead Tuesday night in a bathtub inside the neighbor's apartment, police said.
The man, Esar Met, 21, admitted to authorities that he killed her before trying to hide her body, according to Utah police.
Met, who lived in a row-house style unit at the same complex from which Moo disappeared Monday afternoon, was arrested this morning after he admitted to attempting to hold the child "by force" and she died, according to a Salt Lake County statement.
Met also told authorities he tried to conceal the body and other evidence from the crime scene, according to the statement.
In addition to the aggravated murder charge, Met was booked on kidnapping and evidence tampering charges.
Met was among five people held for questioning after a team of FBI agents found the missing girl's body in a basement bathroom around 9 p.m. inside the South Parc apartment complex.
The four other men were questioned by police and released, Gary Keller, a spokesman for the South Salt Lake City police, confirmed to ABC News.
Keller said additional charges in the case were "probable."
Hser knew some of Met's roommates and frequently went to their apartment to play, Snyder said today.
The girl's father knocked on the door of the unit when he was looking for her, but no one answered, according to police.
Snyder announced the discovery of the girl's body late Tuesday night.
The child appeared to have died from some sort of trauma, Snyder said, but declined to provide additional details. "I will say there is some trauma present and that's all I'm going to say," he said.
Moo had been missing since Monday afternoon when she walked away from her house after an argument with her 10-year-old brother.
The apartment where her body was discovered was the last unit searched by authorities during a daylong sweep of buildings, authorities announced.
Authorities detained four men at the apartment and a fifth at a separate location. Snyder would not say whether there was any connection between the girl's family and the suspects beyond living in the same apartment complex.
Their names were not initially released.
The discovery came just hours after the South Salt Lake police announced at an afternoon briefing that an Amber Alert issued Tuesday was still in effect and that authorities had no new information on the case. Police acknowledged at the time that they were "gravely concerned" about the child's safety.
Hundreds of people came out to help search for the child, whose family came to the United States from Burma in the summer. She was last seen leaving the South Parc apartment complex Monday afternoon after the argument with her brother.
Though the child was reported missing Monday, police issued the Amber Alert Tuesday -- a lag that Snyder has defended.
Moo's father, Cartoon Wah, had pleaded through an interpreter for the public's help finding the girl, his only daughter among five children.
ABC News' Dean Schabner contributed to this report.