Tibbetts, a University of Iowa student, was last seen jogging in Brooklyn, IA, on July 18 while dog-sitting for her boyfriend, Dalton Jack, who was out of town. Police say the boyfriend is not currently a suspect.
FBI agents reportedly searched Cheney's home, some of his property, and his cell phone, and haven't found anything. They were expected to come back and do more searching on Sunday. He told them he had never seen Tibbetts before.
On July 26, FBI investigators reportedly asked to search his property without a warrant and stayed for two hours, taking photos. He hasn't been charged with a crime and said he has "nothing to hide."
"I don't know who those two were but they took me down to the fire station Tuesday and questioned me for two hours," Cheney told local news station WHO-TV. "I don’t remember what they asked me. I just thought it was a waste of time, but, oh well."
The pig farm is in Guernsey, IA, about 10 miles south of Brooklyn. Investigators say Tibbetts is not there.
"I can tell you she's not there. Aside from that, I'm not sure what I'm able to release, but she's certainly not there," Richard Rahn, the special agent in charge with the Iowa Division of Criminal Investigation for the Major Crime Unit, told ABC News on July 27.
According to WHO-TV, Cheney has pleaded guilty in two stalking cases before; one in Poweshiek County in 2009 and one in Marion County in 2014.
Tibbetts, a rising sophomore, was staying at Jack's house for the summer. On the day she disappeared, Jack said he was away for work with his construction company in Dubuque. He said he last saw her on July 16. On the 18th, they talked right before she went on her regular evening run.
"She goes for a run every night. She likes to go whenever the sun's not down," Jack told ABC News. "She knows Brooklyn extremely well, better than I do, and I’ve lived here my entire life."
He also said he opened a Snapchat from her around 10 p.m. that night, although it's not clear when she actually sent the picture. In it, she appeared to be inside. She was last seen wearing dark running shorts, a pink athletic top, and running shoes. People first noticed she was missing when she didn't show up for work the next day, July 19.
Police have followed up on hundreds of leads in the investigation. They've analysed surveillance video from businesses in Brooklyn along Tibbetts' running route, as well as data from her FitBit, which she was believed to have with her while running, and social media.
"If someone has abducted her, we are pleading with you to please release her," Tibbetts' mother Laura Calderwood said in a press conference on August 2. "Every day I feel Mollie's presence with me. Sometimes I just feel her sitting on my shoulder. And Mollie was an incredibly strong young woman, and I don't know that I have the strength in me, and Mollie is lending me her strength every day and every night."
There is a dedicated tip line for the investigation. You can call (00)-1- 800-452-1111 or (00)-1-515-223-1400, or email firstname.lastname@example.org.