Britannica reports that the first historical record of Crucifixion was about 519 BC when "Darius I, king of Persia, crucified 3,000 political opponents in Babylon" (Encyclopaedia Britannica, crucifixion)
Some further detail is given in "The Eerdman's Bible Dictionary", Rev. Ed., 1975: CROSS... Crucifixion is first attested among the Persians (cf. Herodotus, Hist. i.128.2; iii.132.2, 159.1), perhaps derived from the Assyrian impalement. It was later employed by the Greeks, especially Alexander the Great, and by the Carthaginians, from whom the Romans adapted the practice as a punishment for slaves and non-citizens, and occasionaly for citizens guilty of treason. Although in the Old Testament the corpses of blasphemers or idolaters punished by stoning might be handged "on a tree" as further humiliation (Deut. 21:23), actual crucifixion was not introduced in Palestine until Hellenistic times. The Seleucid Antiochus IV Epiphanes crucified those Jews who would not accept hellenization (Josephus Ant.xii.240-41; cf 1 Macc. 1:44-50).
Note re people who investigated the resurrection
Gilbert West (1703-1756)
Gilbert West was included in Samuel Johnson’s Lives of the Most Eminent English Poets. As a student at Oxford, West set out to debunk the Bible’s account of Christ’s resurrection. Instead, having proved to himself that Christ did rise from the dead, he was converted. West published his conclusions in the book Observations on the History and Evidences of the Resurrection of Jesus Christ (1747). On the fly-leaf he had the following printed: “Blame not before thou hast examined the truth.”
Albert Henry Ross (Frank Morison) (1881-1950)
Albert Ross was a lawyer, journalist, and novelist who grew up in Stratford-on-Avon, England. He was deeply affected by the skepticism of the times, particularly the attacks on the Bible by theological liberalism and Darwinism. After becoming a lawyer, he set out to write a book to disprove the resurrection of Jesus Christ. Instead, he was converted and wrote a book in defense of the resurrection entitled WHO MOVED THE STONE? -- which is still in print today. He wrote the book under the name of Frank Morison.
Simon Greenleaf (1783-1853)
Simon Greenleaf, Royal Professor of Law at Harvard University, was one of the most celebrated legal minds in American history. His Treatise on the Law of Evidence “is still considered the greatest single authority on evidence in the entire literature of legal procedure.”
As a law professor, he determined to expose the “myth” of the resurrection of Christ once and for all, but his thorough examination forced him to conclude, instead, that Jesus did rise from the dead. In 1846 he published An Examination of the Testimony of the Four Evangelists by the Rules of Evidence Administered in the Courts of Justice.
Thus, one of the most celebrated minds in the legal profession of the past two centuries took the resurrection of Christ to trial, diligently examined the evidence, and judged it to be an established fact of history! And this was in spite of the fact that he began his investigation as a skeptic.
One of Greenleaf’s points is that nothing but the resurrection itself can explain the dramatic change in Christ’s disciples and their willingness to suffer and die for their testimony.
Josh McDowell, the author of Evidence That Demands a Verdict, was a skeptic when he entered university to pursue a law degree. There he met some Christians who challenged him to examine the evidence for the Bible and Jesus Christ.
Lee Strobel has a law degree from Yale University and worked as an investigative reporter for one of America’s largest newspapers, the Chicago Tribune. He was an atheist. After his wife became a Christian in 1979, he was upset at her decision and determined to prove that the Bible is not true and that Jesus Christ is not the Son God. For two years he pursued this objective, using all of his legal and journalistic skills, but in the end he had proved to himself that the Bible is the Word of God and Jesus rose from the dead. He became a Christian in 1981 and has since written many books defending the Christian faith.
“It wasn’t a phone call from an informant that prompted me to reexamine the case for Christ. It was my wife. Leslie stunned me in the autumn of 1979 by announcing that she had become a Christian. I rolled my eyes and braced for the worst, feeling like the victim of a bait-and-switch scam. I had married one Leslie--the fun Leslie, the carefree Leslie, the risk-taking Leslie--and now I feared she was going to turn into some sort of sexually repressed prude who would trade our upwardly mobile lifestyle for all-night prayer vigils and volunteer work in grimy soup kitchens.
“Instead I was pleasantly surprised--even fascinated--by the fundamental changes in her character, her integrity, and her personal confidence. Eventually I wanted to get to the bottom of what was prompting these subtle but significant shifts in my wife’s attitudes, so I launched an all-out investigation into the facts surrounding the case for Christianity.