Did Cheyann Klus just skip town and leave her friends and family in Chicago? Or is something more sinister at play?

For months, Cheyann's aunt Sylvia Munguia has held on to one desperate hope: That this is all just one bad dream.

Cheyann Klus, 22, turned heads every time she walked into a room. And Cheyann relished the attention.

But the young girl who felt life was an open door would suddenly find it slammed shut as Cheyann watches her mother die from a slow and painful liver failure.

After her mom's death, Cheyann's Facebook posts, once a timeline of selfies and memes, become a catalogue of unbelievable grief, a place where Cheyann pours out her heart to her departed mom.

"She was depressed," said Cheyann's friend Chad Chanapai. "She was going through a lot of tough things with the death of her mom, and her dog passed away around the same time, and those two were her pride and joys and love."

But Cheyann found there were plenty of boys right there to catch her fall. One of Cheyann's new friends is Brian Biddle.

"From what I understood the person that she was seeing on occasion was Brian," said Sylvia.

At the age of 38, Brian Biddle is almost two decades older than 22-year-old Cheyann. Brian Biddle loves to party, and that's just the distraction the grieving Cheyann craves.

"Everybody's has their demons," said Chad. "That's why it always worried me that she was out in these places with these people and partying and stuff like that. Who knows what could happen?"

It's a week after Thanksgiving 2017.

"From what I understood, she took her laptop and maybe a few pieces of clothing, and that's about it," said Sylvia.

Brian Biddle sends an Uber to pick Cheyann up. At Biddle's house, it's an all-day, all-night private party, just Brian and Cheyann.

"He said that she was being her normal self and that they were drinking and partying late into the night," said Chad.

But a day and a half later, just after sunrise, Chad's phone blows up with a flurry of urgent text messages.

"To me she was saying 'Babe, can I get picked up,'" said Chad. "This was early in the morning and I was asleep."

Chad sees the messages just 20 minutes later, but it's 20 minutes too late.

"I texted her and called her back and she wasn't responding," said Chad.

Brian Biddle says he has no idea where Cheyann is.

"He said he was sleeping for 18 hours, and when he woke up, she was gone," said Sylvia.

No phone calls, no Facebook posts, Sylvia says that's nothing like the Cheyann she knows.

"I know she's been gone sometimes by her friends for, you know, days, week at a time, maybe a week and a half, but never this long," said Sylvia.

Twelve days later, Cheyann Klus reappears -- but not in the way the family expects, and it only adds to their feeling of dread.

"A phone call was made from her phone on December 11th to 911," said Missing Persons Awareness Network President Gia Hoffman.

And that single mysterious phone call gives police more than they ever expected.

Cheyann Klus, 22, has vanished. Then 12 days later someone using her phone dials 911, but before the operator can say a word, the caller hangs up.

The last time Chad Chanapai heard from his best friend, she was asking for a lift. But did Cheyann Klus actually need a ride, or an escape plan?

"She continued to text Chad and say 'Chad, please answer the phone, why aren't you answering the phone, please come and get me,' and when he finally responded, she stopped responding forever," said Missing Persons Awareness Network President Gia Hoffman.

For the rest of that week and all through the next, no word, no sign of Cheyann.

After 12 days questions are swirling around detectives' heads. And Cheyann's family believe time is running out and they beg for her return.

Then on December 11, 12 days after anyone has heard from Cheyann, a beacon out of the blue.

"A phone call was made from her phone on December 11th to 911," said Hoffman.

A call to 911 from Cheyann's phone, then a hang-up before a single word is spoken. Was it Cheyann? Or the chilling alternative -- was someone trying to throw investigators off the trail?

DuPage County Sheriff's Detective Jeff Leonard says he doesn't know who made the call, but he soon finds out where it was made.

The call to 911 pings on a cellphone tower at the Mallard Lake Forest Preserve, 20 miles from Brian Biddle's house, 18 miles from Cheyann's home.

It's the best and only lead anyone has. DuPage County officers and K-9 units scour the 86-acre preserve, then again four months later. The searches turn up a few possible pieces of potential evidence.

"Some things were found that were collected as possible evidence but unable at this time to link it to anybody," said Det. Leonard.

Cheyann's friends and family are tortured, and cops are frustrated. No cell phone is found, and worse, no Cheyann.

"We're treating this as a missing persons case, and until she is found deceased, then I'm considering her to be alive," said Det. Leonard.

Gia Hoffman thinks a search of Mallard Lake is worth another try.

There's different areas of water, different hills, there's a lot of trails that go around. Hoffman organizes a volunteer army to scour the 86 acres of forest and brush once more.

"We actually did go inch by inch," said Hoffman.

Cheyann's aunt Sylvia Munguia joins the search for any hint of Cheyann. Hopes are high that this time, some sign of Cheyann would turn up. But once again, nothing was found.

"In this case, somebody does know something. They're just not coming forward yet," said Hoffman.

One person who Gia Hoffman claims hasn't completely come forward is Brian Biddle, the last person known to see Cheyann Klus.

"I know he knows a lot more than he's saying," said Hoffman.

Hoffman says it's time for Biddle to get a wake-up call and answer the questions about what he knows.

"He's not reaching out to anybody, he's not responding to anybody, and it leaves a big gap with one big question: She was last with you. How did you not know that for 18 hours something was wrong?" said Hoffman.

Det. Jeff Leonard says Biddle isn't a suspect in Cheyann's disappearance, isn't even a person of interest. In fact, police say Biddle is talking, and he's a valuable witness.

"Brian is just a witness," said Det. Leoanrd. "Brian is cooperating with us, he gave us all the information that we're looking for. He let us search his home, he let him search his personal devices, his phones, his computer and everything else like that."

Crime Watch Daily tried to reach Brian Biddle to see if he could tell us anything more about where Cheyann could be. We reached out by phone, through Facebook, even went to his house in Chicago, to no avail. Then we found out why.

In our efforts to find him, we discovered he's in Cook County Jail, booked on charges of possession of a firearm and narcotics, unrelated to the disappearance of Cheyann Klus.

With him in custody our questions to Biddle go unasked and unanswered.

"From what I've heard of Brian's background, he was involved in drugs and maybe, I don't know, maybe something could have gone wrong," said Sylivia Munguia.

But those fears can't stop Cheyann's family from hoping that Cheyann does come home. And Sylvia can honor a final wish she made to Cheyann's mom.

"My sister always said 'Will you look after her once I'm gone?'" said Sylvia. "We just have to know she's OK."

Cheyann Klus is now 23. She's described as standing 5 feet 5 inches tall, weighing 115 pounds, with distinctive tattoos on her arm.

If you know anything about her disappearance, contact the DuPage County Sheriff's Office at (630) 407-2569.