Catechism of the Catholic Church §2269 — excerpt
The fifth commandment forbids doing anything with the intention of indirectly bringing about a person's death. the moral law prohibits exposing someone to mortal danger without grave reason, as well as refusing assistance to a person in danger.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.