Not being a suspect means nobody came to him with any questions, no witness saw him, no evidence of him was ever found. The police never had Kokomani under their nose. He wasn't connected to the murder at all and would have never been connected had he not come forward himself. Had he been involved somehow there would have been no reason to come forward to 'muddy the waters'. These waters were already pitch black when it came to Kokomani.
The only possible reason that he did come forward is that he was not involved himself, and that indeed he knew who killed Meredith. He identified all 3 at the crime scene. However, by the time he testified he was already in jail for his drug problems and he couldn't be bothered anymore to give a clear testimony. He even refused a translator. Hardly anyone could understand a word he was saying
AK and RS interjected themselves right from the start since AK lived there and they had cleaned/staged the crime scene. They knew they had quite a few things to 'explain'.