In capital cases witnesses may be called in behalf of the state to rebut or explain any evidence of new matter offered by the defendant, or to discredit his witnesses, though the names of such witnesses have not been furnished to the defendant, but time may be allowed the defendant to answer such evidence, if, in the opinion of the court, justice shall require it.
RSA 606:6
1843, 34:17. CS 240:4. GS 243:11. GL 261:11. PS 254:12. PL 368 :14. RL 428:14.