The night before his execution Con Colbert sent for Mrs. Ó Murchadha who was also being held prisoner. He told her he was "proud to die for such a cause. I will be passing away at the dawning of the day." Holding his bible, he told her he was leaving it to his sister. He handed her three buttons from his volunteer uniform, telling her "They left me nothing else," before asking her when she heard the volleys of shots in the morning for Eamonn Ceannt, Michael Mallin and himself would she say a Hail Mary for the souls of the departed. The soldier who was guarding the prisoner began crying according to Mrs. Ó Murchadha, and recorded him saying "If only we could die such deaths."
Colbert was shot by firing squad the next morning on 8 May 1916 in the breakers yard of Kilmainham Jail. .