(CNN) Police are searching for a 5-year-old Utah girl who went missing from her family's home Saturday morning.

Elizabeth Shelley was last seen with her uncle, 21-year-old Alex Whipple, who police arrested Saturday afternoon on unrelated probation violation charges.

Police say he is the main suspect in the case, which will "not end well," but they have not explained why.

"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 lack of details of this investigation," Logan City Police said in a Facebook post.

"They do not have all the information because we cannot release everything pertinent to this investigation."

So here's what we know and don't know so far.

When Elizabeth was last seen

Elizabeth was last seen at home in Logan City -- about 80 miles north of Salt Lake City -- by her mother on Saturday at 2 a.m., according to Logan City Police Capt. Tyson Budge.

Whipple showed up at the home on Friday night and they were all together at 2 a.m., police said . When they woke up in the morning a little after 9 a.m., though, they couldn't find Elizabeth and Whipple was no longer in the home, police said.

The family searched for a while and then called police around 10 a.m.

We don't know when she left her home or with whom she left.

What Elizabeth looks like

According to the police missing poster, Elizabeth is three feet six inches tall, weighs 40 pounds and has a slim build. She has brown eyes and brown hair, which she wears just past the shoulders.

She is white and of fair complexion and is believed to have been wearing a red tank top and blue jeans.

Her uncle's movements

Whipple had come to the family's home for a visit on Friday night and was last seen around the same time as his niece, police say.

Alexander Whipple, 21, was arrested early Sunday.

CNN affiliate KSTU said police had confirmed Whipple had been seen on surveillance video at the Hyrum Shortstop gas station Saturday afternoon.

It quoted a staff member as saying that Whipple had come into the store alone about 1:30 p.m. Saturday looking "disheveled, like he had been on a binge of some kind." Whipple bought cigarettes and beer, the employee said, according to KSTU.

Cache County deputies located Whipple at about 3 p.m.. He failed to identify himself and had a warrant for his arrest for not checking in with probation after recent charges of receiving stolen property and driving under the influence, Logan City Police said. He was also in possession of drug paraphernalia, police said.

Detectives interviewed him and he lied, police said.

"Mr. Whipple made several inconsistent statements at the very beginning and lied about his whereabouts which were already known. He was uncooperative throughout the interrogation," Logan City Police said

But we don't know Whipple's movements between Elizabeth's house and Hyrum and police are asking for any sightings of him Friday evening onward.

Where police are searching

The search spans a 20-mile range at south end of Cache County -- from Elizabeth's residence to where they found the suspect, KSTU reports.

Police have asked residents in the Logan, Nibley, Hyrum and Mount Sterling areas to watch for any suspicious items on their property.

They have also asked businesses or residences with outdoor camera systems or doorbell cameras to review the footage for suspicious activity

We don't know what specific items they are seeking.

What evidence police have recovered

"We were able to obtain some new information this morning, some evidentiary items that we've located, so we believe that we'll locate her," KSL quoted Budge as saying. "There are several locations where we believe we've found evidentiary items that'll help link Mr. Whipple to this case."

But we don't know what the items are.

Which agencies are conducting the search

Police said Sunday that additional search and rescue support had been called in from several other counties. The search has been expanded to the Hyrum area and we continue to work leads that have come forward. We now have over 200 individuals assisting in the search effort," the police department said on Facebook Sunday evening.

KSL said Logan City Police, the Cache County Sheriff's Office, Cache County Search and Rescue, the FBI's Child Exploitation Task Force and the Utah Department of Public Safety were involved in the search.

But we don't know why they have concerns about the outcome of the search.

Budge, the police captain, told CNN the case is "not going to end well."

Where Whipple is being held

Whipple was located Saturday and arrested on a warrant for a probation violation, police said. He was booked into Cache County jail and was being held Sunday on $25,000 bond. Elizabeth was not with him when he was found, police said.

KSTU says Whipple also faces unrelated drug and gun-related charges.

But we don't know why police have made Whipple the main suspect.

"All I can say at this time, is we have evidence to believe that he is the reason that she is missing," KSTU quoted Budge as saying.