Rep. Paul Gillmor (R-Ohio) passed away suddenly Tuesday night, according to his office. He was 68. 

According to an inter-conference email obtained by The Hill, Gillmor did not show up to the office this morning causing his staff to become concerned. When they went to his apartment to check on him, they found that the lawmaker had passed away.

Capitol Police is currently investigating, but sources believe that the 10-term lawmaker may have had a heart attack.

In November, Gillmor won his district with 57 percent of the vote, holding on to his seat in a year that saw Democrats take over a GOP Senate seat and the governor’s mansion in Ohio.

A special election will be necessary to find someone to fill out the rest of the term. While Republicans are favored to retain the seat, such an election will likely be costly and an added burden to the GOP.