In verse 5 it says that after they saw the murdered judge they believed, but this merely means that they believed what Nephi had said concerning the murder of the judge. Their conversion will come later. However, the shock of finding the judge weltering on the ground in his own blood had a powerful physical impact on these five men. They fainted.
Meanwhile, the servants of the judge had gone out into the streets and raised a cry of alarm.
6. Now, immediately when the judge had been murdered -- he being stabbed by his brother by a garb of secrecy, and he fled, and the servants ran and told the people, raising the cry of murder among them; 7. And behold the people did gather themselves together unto the place of the judgment-seat -- and behold, to their astonishment they saw those five men who had fallen to the earth.
6. Now, immediately when the judge had been murdered -- he being stabbed by his brother by a garb of secrecy, and he fled, and the servants ran and told the people, raising the cry of murder among them; 7. And behold the people did gather themselves together unto the place of the judgment-seat -- and behold, to their astonishment they saw those five men who had fallen to the earth.
When a crowd gathers in a crisis such as this, they immediately began jumping to conclusions. This is what happened here. The crowd decided they knew exactly who had committed this murder. As the record says:
“And now behold, the people knew nothing concerning the multitude who had gathered together at the garden of Nephi; therefore they said among themselves: These men are they who have murdered the judge, and God has smitten them that they could not flee from us. And it came to pass that they laid hold on them, and bound them and cast them into prison. And there was a proclamation sent abroad that the judge was slain, and that the murderers had been taken and were cast into prison.”