Though the New Testament claims Jesus Christ was publicly killed, it says there were no human witnesses of Jesus Christ exiting his tomb, not even Mary Magdalene - see Matthew 28:2-7, 11-15 and Mark 16:1-8. [Mark 16:9-20 is not in the earliest extant manuscripts; see the translators' note pertaining to it in the NASB--Updated Edition which says "Later mss add vv 19-20". (The 2013 NWT is thus justified in excluding them.)] Note that Matthew 28:14 (NASB--Updated Edition) says that when guards saw the angel they became "like dead men", which can mean they fell down and became unconscious. That is in harmony with the Jewish elders telling the guards to say that they (the guards) were asleep (as stated in verse 13) when the body of Jesus left the tomb (albeit with the elders telling the guards to say that the dead body of Jesus was removed by the disciples of Jesus).
The New Testament says there were no human witnesses, other than some of Jesus' disciples, of the alleged resurrected/recreated risen Christ being seen prior to his alleged ascension to heaven and likewise during his alleged ascension to heaven.
The New Testament provides no testimony at all of the alleged risen Christ (whom many say is God) revealing himself to those not believing in his divinity, with the exception of Saul (later renamed Paul). But, the NT accounts makes it appear that the accounts claim that Paul saw a vision of Christ rather than saw Christ himself.
There are also some contradictions of the accounts recorded in Acts of Paul's alleged encounter with the supernatural risen Christ. Some modern scholars say that Paul instead of seeing and hearing Christ and instead of having a supernaturally induced vision of Christ, was experiencing a temporal lobe seizure and that during that he hallucinated seeing and hearing Christ. They say the accounts of what Paul saw and heard, including his vision of being taking to the third heaven, and of Paul's health problems fit the medical condition of experiences of temporal lobe seizures, including having hallucinations.