At first glance, Jesus appears to strictly support the ‘two witness’ rule here:
John 8:16-18 “But if I do judge, my decisions are right, because I am not alone. I stand with the Father, who sent me. 17 In your own Law it is written that the testimony of two men is valid. 18 I am one who testifies for myself; my other witness is the Father, who sent me."
But on further examination, Jesus did not insist on his doubters actually hearing the testimony of two literal witnesses. He showed in the following passages that what mattered was works as evidence of his claims.
John 14: 9 - Jesus answered: “Don’t you know me, Philip, even after I have been among you such a long time? Anyone who has seen me has seen the Father. How can you say, ‘Show us the Father’? 10 Don’t you believe that I am in the Father, and that the Father is in me? The words I say to you I do not speak on my own authority. Rather, it is the Father, living in me, who is doing his work. 11 Believe me when I say that I am in the Father and the Father is in me; or at least believe on the evidence of the works themselves. 12 Very truly I tell you, whoever believes in me will do the works I have been doing, and they will do even greater things than these, because I am going to the Father. 13 And I will do whatever you ask in my name, so that the Father may be glorified in the Son. 14 You may ask me for anything in my name, and I will do it.
John 10: 34 - Jesus replied, “It is written in your own Scriptures[e] that God said to certain leaders of the people, ‘I say, you are gods!’[f] 35 And you know that the Scriptures cannot be altered. So if those people who received God’s message were called ‘gods,’ 36 why do you call it blasphemy when I say, ‘I am the Son of God’? After all, the Father set me apart and sent me into the world. 37 Don’t believe me unless I carry out my Father’s work.38 But if I do his work, believe in the evidence of the miraculous works I have done, even if you don’t believe me. Then you will know and understand that the Father is in me, and I am in the Father.”
Jesus words above show he did not hold to a rigid stance on requiring two personal witnesses in order to establish a claim. If the testimony of himself as one witness didn’t satisfy his doubters then he appealed to the overall evidence. The Biblical principle laid down here by Jesus is that other forms of evidence, which in modern times would include forensic and any other evidence regarded as authoritative by the secular authorities, should be acceptable as a second ‘witness’ to establish guilt in the matter of the Watchtower’s policy on paedophile accusations.