MONTEZUMA, Iowa — The mother of a 20-year-old Iowa college student who vanished nearly two weeks ago says the drawn-out search for her daughter has been torturous. Mollie Tibbetts' mother, Laura Calderwood, told CBS affiliate KCCI-TV that even though Tibbetts has been missing for so long, she is determined to find her daughter.

"The first night she went missing, I was distraught," Calderwood said. "I knew her phone was dead, but I sent her a text saying, 'I love you. We're looking for you. We will find you no matter what.'"

Tibbetts hasn't been seen since going for an evening jog on July 18 in Brooklyn, a community of about 1,400 people where she was living this summer with her boyfriend in a farmhouse.

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Calderwood told the station that the last two weeks have been an "emotional roller coaster" and she sees her daughter's face on posters all over town.

"It's a reality check every time I see one of those posters," she said. "It's like, 'she's gone.'"

Friends say Tibbetts had been planning to travel to the Dominican Republic this week for a wedding.

Blake Jack says his brother Dalton and Tibbetts (Dalton's girlfriend) were supposed to be there when he married his fiancee, Aimee Houghton. He says he joked with his brother that he should propose to Tibbetts during the trip.

The morning after she disappeared, Tibbetts' family reported her missing after she didn't show up to her job at a daycare center in a nearby town.

At a news conference Tuesday, Kevin Winker, director of investigative operations for the Iowa Division of Criminal Investigation, said investigators haven't drawn any conclusions about what happened to Tibbetts other than that disappearing on her own "is not consistent with her past."

He said dozens of investigators from his agency, the FBI and local law enforcement are working on the case, and that they haven't ruled out any possibilities and are checking out every lead they receive.

Blake Jack told The Associated Press on Tuesday that on July 18, he was visiting his fiancee, Aimee Houghton, in Ames, where she is working this summer. He said his brother was working a job for their family construction company about 100 miles away in Dubuque.

He said Tibbetts was taking care of his dogs while they were out of town.

"But what she was doing that night, I have no idea," he said, standing in the driveway of the home.

Blake Jack said the scrutiny on him and his brother is unwarranted, saying that investigators have confirmed their whereabouts on the night Tibbetts vanished. He said the speculation is hurtful, but "the people in this community know the truth."

"We know something had to have happened to her," he said.

Blake Jack repeatedly urged anyone who saw anything unusual - "big or small" - to report it to the authorities. He said his cancelled wedding plans were nothing compared to what the whole community was going through.

Neighbor Dave Collum, a retired maintenance director for the school district, said he was interviewed by investigators who told him that data from Tibbetts' Fitbit showed she jogged past his home that evening and made it home from the run safely. He said investigators told him she was doing homework on her computer later that evening.

Winker declined to confirm that claim at the news conference. He said investigators have a timeline but would not confirm or deny case facts so as not to jeopardize the case.

Collum said he often saw Tibbetts running in the neighborhood but didn't on the night she vanished. He has known her family for years and often sat near them during Mass at the local Catholic church. He said she's not the type of person who would run away, and that he's worried she was the victim of a stalker or a random abduction.

Collum has joined hundreds of other volunteers in searching the area's cornfields and buildings for Tibbetts. He put a magnet with her face on it on his red pickup truck, so he could have a reminder of her every time he gets into it.

"Everybody in town is still trying," he said. "It's sad."