(CBS) — The search continues for a medical student who disappeared last week.

Ambrose Monye, 28, was last seen on April 21, walking towards the University of Chicago’s John Crerar Library, a medical research library at 5730 S. Ellis Av. On Thursday, his family posted flyers around the area, hoping for leads.

Monye is a fourth year med student at University of Guadalajara on a two-year rotation at Jackson Park Hospital and Medical Center. He also worked at a clinic in Hyde Park.

His younger brother tells CBS 2 all the lights were on at Monye’s apartment when police went to check it out, and the refrigerator was full of groceries.

“I can’t even wrap my mind around what possibly could have gone wrong,” Joseph Monye, who also is a medical student, says. “It’s as if he literally disappeared into thin air.”

The brothers are from just outside Baltimore, Maryland, and come from a family of doctors. Joseph Monye said the brothers’ lives revolved around studying and more studying.

“That’s literally all we do, because we don’t want to encounter any kind of problems, so we just keep to ourselves. We focus on our studies, and mind our business, and it’s odd enough this happened,” he said.

There has been no activity on his brother’s phone and credit cards for a week, Joseph Monye said.

“I do worry that something happened to him, to be honest with you. That’s my worst fear and my worst nightmare,” he said. “It doesn’t make any sense. It doesn’t add up. So it only leads you to wonder what could have happened.”

Ambrose Monye was four weeks shy of graduation. Anyone with information about his whereabouts should call Area Central Special Victims Unit detectives at (312) 747-8380.