On Tuesday, Iowa authorities found remains in a Poweshiek County field they suspect are those of missing college student Mollie Tibbetts, a police source told PEOPLE.
It’s still not clear what happened to the teen or how she died.
Mitch Mortvedt, a spokesman for state authorities, told the Associated Press that “there is nobody charged at this time.”
A news conference about the case is scheduled for later Tuesday.
“It’s not the ending we all hoped for at all,” Tibbetts’ friend Alyssa King tells PEOPLE.
Says King, who has known Tibbetts for years: “We are all devastated.”
Here’s what authorities and Tibbetts’ family have said about the timeline of her going missing, as well as the search efforts that led to the presumed discovery of her body.
July 18: She Vanishes, Seemingly Without a Trace
Tibbetts was last seen alive about 7:30 p.m. on July 18 on her regular run around Brooklyn in eastern Iowa, where she lived, according to state authorities. She had been staying at the home of her boyfriend, Dalton Jack, to care for his dogs while he was away at a construction job.
She was wearing dark-colored running shorts, a pink athletic top and running shoes.
“She goes for a run every night,” Jack told ABC News. “She likes to go whenever the sun’s not down, but it’s starting cool off, like 6 or 7. She knows Brooklyn extremely well, better than I do and I’ve lived here my entire life.”
Tibbetts also sent a text message around 7 p.m. on July 18 and Jack opened a Snapchat message from her about 10 p.m., though it’s unclear when she sent it, he has reportedly said. He told ABC the photo was a selfie that appeared to have been taken indoors.
ABC News also reported that her ID and keys were left behind at the house.
July 19: Police Learn of Her Disappearance
Authorities previously told PEOPLE that Tibbetts was reported missing late in the morning on July 19 after she did not show up for work at the Grinnell Regional Medical Center, some 25 minutes away, where she was a camp counselor at a day camp.
Speaking with local TV station WOI in late July, Jack said he first learned Tibbetts had vanished on July 19, when one of her coworkers called and said she “had not called into work that day and she hadn’t showed up.”
He’d texted her that morning but got no response, according to local station KCRG.
“And then I looked at the messages and she hadn’t opened or read the message,” Jack recalled to WOI. “And then I started getting in contact with her friends and family, saying, ‘Have you seen her or heard from her?’ And they all said the same thing: ‘No, we haven’t heard from her since yesterday.’ “
According to WOI, Jack quickly returned to Brooklyn to join the search efforts: “I came home as soon as her mom said that she called the hospital and she wasn’t there.”
July 20: A Large Search Ensues
A massive ground search involving more than 200 people broken up into 37 teams was conducted, encompassing the farmlands and fields within a five-mile radius of Brooklyn, with helicopters hovering above, according to authorities.
Poweshiek County Sheriff Thomas Kriegel told PEOPLE at the time: “At this point, everything is being considered — we are looking at everything and everybody.”
He explained: “We have been working to eliminate areas where she could be at and checking people we might suspect, but who are not suspects yet … we’re just seeing where they were and checking their whereabouts.”
July 25: Investigators Look at ‘Agricultural Property’
Mortvedt told the Des Moines Register that, among “a couple” of property searches in the case was an area off Iowa Highway 21 in the southern part of Poweshiek County but “nothing of investigative value” was found.
The location was described as an “agricultural property” by the Register.
July 26: Pig Farm Searched as Officials Say They’ve Reviewed Digital Information & Surveillance
On July 26, Mortvedt told PEOPLE that local, state and federal officers were following up on a number of leads. He confirmed that detectives were searching a pig farm in Guernsey that morning, about a 15-minute drive from Brooklyn.
Mortvedt also noted several searches were being conducted in and around the county.
Speculation that Tibbetts could not have been abducted by a stranger was misguided, Mortvedt said at the time.
“One avenue of thought is that if it wasn’t a struggle, and we have found no signs of a struggle, then maybe it was someone she was familiar with,” Mortvedt said. “But then the other avenue of thought is it could have been a stranger who simply overpowered her or tricked her. We just have very little to go on.”
Mortvedt said investigators were interviewing a number of people Tibbetts knows or seems to “have a connection to,” including fellow University of Iowa students and her co-workers.
Investigators were also poring over the data recovered from Tibbetts’ social media accounts and her fitness tracker as well as extensive surveillance footage from the area.
Aug. 2: Reward Announced by Family — Who Said They Thought Tibbetts Was Alive
Tibbetts family announce at a press conference the formation of a reward fund for Tibbetts, and said they believed she was still alive.
Tibbetts’ mother, Laura Calderwood, revealed that in just one day, the Bring Mollie Tibbetts Home Safe Reward Fund raised $172,000 for information leading to her daughter’s safe return. [The fund has since raised more than $300,000].
“We believe Mollie is still alive and if someone abducted her, we are pleading with you to please release her,” she said. “It is our greatest hope that if someone has her, they will just release her.”
Aug. 7: Dad Addresses Possible Abductor: ‘Do Not Escalate This .. .Let [Her] Go’
Tibbetts’ father Rob appeared on Fox News and urged a possible abductor to “turn yourself in” and “let Mollie go.”
A day earlier, Rob spoke to ABC News, saying that he believed his daughter was being held by someone she knows.
“It’s totally speculation, but I do believe that Mollie is with someone who she knows, probably someone who cares about her,” Rob said. “But that relationship was misguided, misinterpreted and went wrong, and I think they’re in a place with Mollie and don’t know how to get themselves out of this horrible situation.”
Aug. 14: Authorities Zero in on 5 Locations in Brooklyn Area
Investigators identified five locations near where Tibbetts was last seen they said could be connected to her case.
According to a state website dedicated to finding her, “law enforcement is currently seeking additional witnesses and wants to speak to anyone who was in [the five areas] … on July 18, 2018 between the hours of 5 p.m. and 10 p.m.,” which is within a few hours of when Tibbetts was spotted on her regular evening run.
The site featured a map with the five locations, which included a highway truck stop, a car wash, two tracts of farmland, as well as the area surrounding Tibbetts’ boyfriend’s house.
The website also asked for residents to be alert to any sudden changes in behavior they may detect in friends, relatives and co-workers such as changes in a person’s physical appearance, displays of anxiety, nervousness or irritability, unexplained injuries or changes in consumption of alcohol or drugs or “interest in the status of the investigation” and an unwillingness to discuss it.
Aug. 21: Police Believe They’ve Found Tibbetts’ Remains
Nearly a month after she was reported missing, police announced they believed they’d found the remains of Tibbetts in a field in Poweshiek County, although although confirmation the remains are hers are pending.
A news conference in the case is scheduled for later Tuesday.
Tibbetts’ friend King says Tibbetts’ loved ones are grieving.
“It’s definitely not going to be easy, not for a long, long time,” she says. “But we’ve got a pretty sweet angel with us all … and we will continue to spread her love and life to everyone.”
Aug 21: Suspect Identified as Cristhian Bahena Rivera, 24
During a press conference, Iowa authorities announced they had charged Cristhian Bahena Rivera with first-degree murder. The 24-year-old was first approached by investigators after his car was spotted in footage captured by security cameras that showed Tibbetts jogging.
Police allege Rivera confessed to approaching Tibbetts while she was running, saying he ran alongside her. At one point, Tibbetts told Rivera to leave her alone and threatened to call police, Rivera allegedly confessed.
Subsequently, Rivera allegedly chased Tibbetts down and said he blacked out at some point, Rahn said.
Rahn would not say how Tibbetts was killed and would not comment on a possible motive, saying only that Rivera “seemed to be drawn to her on that particular day and chose to abduct her.”
Rahn said Rivera admitted to seeing Tibbetts before, but said that “beyond that, I won’t be able to say anymore about his interactions with Ms. Tibbetts.”