The father of a missing teenage girl who was abducted by an armed man in Anchorage, Alaska, is pleading for the kidnapper to send his daughter home.

Samantha Koenig, 18, was last seen Wednesday evening on surveillance video that showed her leaving the Common Grounds Espresso stand with an armed man, who police said was wearing a dark hooded sweatshirt and possibly a baseball cap.

All of the coffee stand's cash was also missing.

"Please send my daughter home. I will give you anything in this world," said her father, James Koenig.

"I don't know if my daughter's being fed, taken care of, if she's alive, getting sleep," he added.

At least two dozen detectives are working to sort through leads in the case, according to local media reports.

Police and volunteers are currently braving sub-freezing temperatures to search for Koenig.

"The longer we go without knowing where Samantha is, the more difficult the case becomes," said Lt. Dave Parker of the Anchorage Police Department.

"They left on foot, we know that much, but beyond that her disappearance became a complete mystery," said Parker.

Koenig's father announced at a press conference Saturday that a $12,500 reward, donated by friends and family, is now being offered for information about his daughter's whereabouts.

Koenig's friends and family are collecting donations to put towards the reward.

"We're giving out lime green ribbons for donations. It's her favorite color," said Koenig's boyfriend of nine months, who asked to be referred to by his first name, Dwayne.

Koenig filed for a protective order against a man in November, the Alaska Daily News reported, however the order was not issued after she failed to appear in court.

"This isn't in Samantha's nature. She's a good-hearted girl. This doesn't need to be happening to her, so we need to find her as soon as possible," said Dwayne.