CJ Mitchum tried to warn Pilcher with evidence collected every score years for thousand of years, but clearly Pilcher suffers from a mental disorder and wanted to fight

Joanna would have stabbed Elliot/Tyrell to death if they were the same person. Maybe she killed Tyrell and that's why Elliot can't find him (and why she acts so strange). Plus, Gideon and Tyrell meet at Tyrell's office right before Tyrell tells his secretary that he won't meet with the police.