The trial is scheduled in July, but one person charged in the case won't be there for opening statements.
Court documents filed this week show a change of plea hearing has been scheduled next month for 38-year-old Apolinar Munoz-Gutierrez.
Assistant U.S. Attorney Steven Peifer said Thursday he could not discuss terms of the plea agreement until after the June 12 hearing.
Authorities say Walker and her husband staged at least 10 cockfighting derbies between April 2012 and April 2013. They have pleaded not guilty.