The more one reads the Pliny letter to Trajan the more it does not make sense.
1. Pliny first executed all those who admitted they were presently Christians except Roman citizens.
2. The Roman citizens who admitted they were Christians were sent to Rome for trial.
3. Some of remaining persons claimed that they were never Christians, cursed Christ, worshiped the statue of Trajan and were released.
4. Pliny then tortured some of others to find out what they believed when they were Christians.
It makes no sense whatsoever for Pliny to have executed Christians if he did know what punishment they deserved and then to torture non-Christians who cursed Christ and worship the statue of Trajan to find out what Christians believed up to 25 years earlier.
In effect, Pliny is writing to Trajan to find out what to do with people who denied that they were Christians and who worshiped Trajan as a God for up to 25 years.
Pliny letter to Trajan
Others named by the informer declared that they were Christians, but then denied it, asserting that they had been but had ceased to be, some three years before, others many years, some as much as twenty-five years. They all worshipped your image and the statues of the gods, and cursed Christ.