The change in teaching did not become confirmed until 1997.
The change was prompted by an error by Pope John Paul II and such error was placed as an amendment into the CCC, with no one fact checking.
Re: CCC 2267:
from Kevin L. Flannery S.J., Consultor of the Sacred Congregation for the Doctrine of the Faith.
Flannery was, also, appointed by SPJPII.
“The most reasonable conclusion to draw from this discussion is that, once again, the Catechism is simply wrong from an historical point of view. Traditional Catholic teaching did not contain the restriction enunciated by Pope John Paul II." (4).
“The realm of human affairs is a messy one, full of at least apparent inconsistency and incoherence, and the recent teaching of the Catholic Church on capital punishment—vitiated, as I intend to show, by errors of historical fact and interpretation—is no exception.” (4)
“Capital Punishment and the Law”, Ave Maria Law Review, 2007 (30 pp), by Kevin L. Flannery S.J., Consultor of the Sacred Congregation for the Doctrine of the Faith (since 2002) and Ordinary Professor of Ancient Philosophy at the Pontifical Gregorian University(Rome) and Permanent Research Fellow - Mary Ann Remick Senior Visiting Fellow at the Notre Dame Center for Ethics and Culture (University of Notre Dame.
lr.avemarialaw.edu/Content/articles/V5i2.flannery.copyright.pdf