The search continued Monday for a 5-year-old girl in Utah who was reported missing over the weekend, and police have identified her uncle as the "main suspect" in her disappearance.

Elizabeth Shelley Logan City Police Department

Family members told police Elizabeth Shelley, of Logan, was last seen at 2 a.m. on Saturday when her mother went to bed. When she woke up at about 9:30 a.m., Elizabeth was gone, as was her uncle, Alex Whipple, 21, who had visited the house Friday night, the Logan Police Department said. Logan is about 80 miles north of Salt Lake City.

Whipple, who police have said is the main suspect, was later found walking around the northern Utah city alone and was arrested Saturday.

Police said he continued to be uncooperative and was booked into the Cache County Jail on a probation violation.

"The unfortunate thing is that we have all the adults accounted for," Logan police Capt. Tyson Budge told NBC affiliate KSL in Salt Lake City Saturday. "So obviously, conclusion is that she's in a lot of danger."

Alex Whipple Logan City Police Department

Whipple was in possession of "certain items," such as clothing, that authorities believe indicates the uncle "was with her after he said he was," Budge told the outlet. He also was in possession of "drug paraphernalia," the police captain said at a brief news conference on Monday.

Authorities have said they could not release more information on Elizabeth's disappearance, citing an ongoing investigation.

"We know there are many who want to help and there are some who think they are helping by posting their concern about the perceived details of this investigation," the Logan Police Department said in a tweet. "They do not have all the information because we cannot release everything pertinent to the investigation."

The FBI is assisting in the search for Elizabeth.

In a statement read at the Monday news conference, Elizabeth's family said they were "overwhelmed, sad and scared." They thanked law enforcement and search volunteers for their efforts, adding that they "continue to hope for the safe return of our sweet girl, Lizzie."

Elizabeth is 3 feet 6 inches with shoulder-length curly brown hair and has choppy bangs and brown eyes.