It was a legal process. Even though the trial was not held under Roman law, the Chief Priests were still bound by the principles in the Old Testament law. The rules of evidence in Deuteronomy 19:15-21 demanded that an accusation should not be upheld against an accused person unless two or three independent witnesses gave the same evidence of the crime. Also the judge must make a thorough investigation of the accusation and the defendant was allowed to explain his case.

Peter should never have been in that courtyard mixing with the soldiers and servant girls. His arrogance, pride or bravado took him there. Perhaps it was his misplaced sense of responsibility for Jesus. Whatever it was, he failed to live up to his own expectations that night. His accent (from Galilee in the north) gave him away, and many people would have seen the distinctive fisherman with Jesus.
 

Something very ugly happens when a human life is calculated in money. It turns people into a commodity to be traded. His or her value is the highest price anybody will pay for them, in anticipation of getting something out of them. Exploiting human beings is normal (but not right) in a sinful world where people are greedy for power or profit; however it is dressed up, it is slavery. And where people stand in their way, they may pay blood money to get rid of them.

Pilate, the Roman Governor, had a poor reputation among the people in Israel. His violence against the people was savage and unpredictable: they did not trust him. So, more in the interests of politics than justice, Pilate offered a 'prisoner swap' once a year to appease the people who thought someone was being treated unfairly. It was a way for Pilate to win popularity