VATICAN CITY — Pope Francis says nothing can justify the use of the death penalty and there is no “right” way to humanely kill another person.

Francis outlined the Catholic church’s opposition to capital punishment in a letter to the International Commission against the Death Penalty, a group of former government officials, jurists and others who had an audience with him at the Vatican on Friday.

The pope wrote that the principle of legitimate personal defense isn’t adequate justification to execute someone.

“When the death penalty is applied, it is not for a current act of aggression, but rather for an act committed in the past,” he said.

“Nowadays the death penalty is inadmissible, no matter how serious the crime committed,” Francis declared.

He was building on church teaching, including pronouncements during St. John Paul II’s papacy, that modern prison systems make executions unnecessary.

Capital punishment “does not render justice to the victims, but rather fosters vengeance,” Francis added.