Kosta Karageorge, a 22-year-old senior defensive tackle from Columbus, was last seen at his apartment around 2 a.m. Wednesday. Team spokesman Jerry Emig confirmed that Karageorge missed practice Wednesday and Thursday, which his family says was uncharacteristic.
Karageorge's parents filed a missing-person report Wednesday evening, listing him as white, 6-foot-5, 285 pounds, bearded and bald.
His mother, Susan Karageorge, told police he has had several concussions and a few spells of being extremely confused, according to the report. She said at about 1:30 a.m. Wednesday he texted a message that cited the concussions and said, "I am sorry if I am an embarrassment."
The team's physician, Dr. Jim Borchers, said Friday that he could not comment on the medical care of student athletes. But, he said, "We are confident in our medical procedures and policies to return athletes to participation following injury or illness."
The player's sister, Sophia Karageorge, told The Columbus Dispatch that he apparently was upset, and roommates said he went for a walk, dressed in black from his hat to his boots.
"We're very concerned that he's not himself and that he maybe doesn't know what's going on," she told the newspaper.
She said after each concussion he followed trainers' instructions and received proper care but "his repercussions from (concussions) have been long-term or delayed."
She said he was without his wallet and his motorcycle.
Columbus police are investigating Karageorge's disappearance as a missing-person case, the Dispatch reported.
"Certainly a young adult male is allowed to go off the grid for any period of time," police spokesman Sgt. David Pelphrey told the newspaper. "At this point, the family has expressed some concerns, and in response to their concerns we're ramping up our efforts."
Kosta Karageorge, a former Buckeyes wrestler, joined the football team as a walk-on this season. He has played in one game and is among two dozen seniors slated to be recognized at their final home game Saturday against rival Michigan.
Ohio State coach Urban Meyer described him as a hard worker and an important player in practice.
"Our thoughts continue to be with the family of Kosta Karageorge, and we pray that he is safe and that he is found soon," Meyer said in a statement.
During halftime at the No. 16 Ohio State men's basketball game against James Madison in Columbus, pictures of Karageorge were shown and an announcement was made urging people with any information to contact police.
About 100 people gathered Friday afternoon in Columbus to spread fliers with his photo and description.
Associated Press writers Rusty Miller and Kantele Franko contributed to this report.