The woman is not guilty of the charge made against her by the Pharisees, the Pharisees knew this, they were guilty of lying, they knew it, they could not stone her under the law, there would have had to be a man present who was also guilty, they both needed to be caught, and there needed to be two witnesses, yet 'no man accuses me', so the case is illegitimate. To show that the Lord knew their thoughts and knew that this was another man's "wife", He complied with the law prescribed in Numbers 5:11-31.
"Again He stooped down and wrote on the ground, And they that heard it being convicted by their own conscience" 8 John 8:8-9
Jesus wrote the curse on the ground; "The LORD make thee a curse and an oath among thy people" and "the priest shall write them in the book" Num. 5:23.
Jesus dismisses the Pharisees case and conducted a new case with Him as LORD pronouncing a curse and as High Preist He writes on the ground.
The Pharisees were still there but the others who had gone along with the Pharisees against the woman had left, because it says 'they went out one, by one', but the Pharisees were still there, and they accused Jesus this time, because they did not have two witnesses, you see the witnesses, the people would have had to stone the woman, NOT the Pharisees, they could not stone the woman, they themselves could not carry out the execution by their own hand, just like they could not execute Jesus, they got the Romans and other Judeans to carry out the execution, but the people had left, they were convicted by their own conscience, no man was left to condemn the woman to death, Jesus di not condemn her because she was not guilty of the crime put against her by the Phasiees, but she was guilty under the law of jealousy, and the LORD knew this and He wrote the curse on the ground, the woman had sinned but the Phaisees were using her, if they could get the people to stone this woman, and she was innocent, then the Pharisees would have successfully decieved Jesus. But they did not decieve Him and He judged correctly, so the Pharisees accuse Him of not having two witnesses, so it's like saying, 'you claimed we did not have the witnesses, but where are yours, you need two, you cannot judge of yourself', but Jesus answered that He can, He says He has His Father in heaven as His witness....