The judge said he will take up later the issue of whether jurors can be told of the relationship.
After the hearing, Scott Adams told news reporters that Mitchell is “looking forward to getting in front of a jury ... getting acquitted and getting this nightmare behind him.”
The attorney also said Mitchell is hopeful that the gambling case may somehow help identify who killed his wife.
Julie Mitchell, 34, was beaten to death in the couple's northwest Oklahoma City home on Nov. 2, 2010. Oklahoma City police are investigating the homicide.
Scott Adams said, “I would like to remind everyone that there's a $50,000 reward out there” for information about Julie Mitchell's death.
“If any of this helps bring those people forward, that's all we're begging for at this point,” the attorney said.
A federal grand jury last month indicted Mitchell, two of his sons, six other men and a Costa Rican company. The grand jury alleged the illegal gambling took in at least $8.1 million.
Mitchell contends he is a professional gambler who acted legally. He is on home detention while awaiting trial.