Special verdict where accused person found guilty but insane at date of act or omission charged

Where in an indictment any act or omission is charged against any person as a crime, and it is given in evidence on the trial of that person for that crime that he was insane, so as not to be responsible, according to law, for his actions at the time when the act was done or the omission made, then, if it appears to the jury before whom the person is tried that he did the act or made the omission charged, but was insane as aforesaid at the time when he did or made it, the jury shall return a special verdict to the effect that the accused person was guilty of the act or omission charged against him, but was insane as aforesaid at the time when he did the act or made the omission. per-son found