Defense attorney Gary Mark Feldman says Walker will plead guilty to theft and be sentenced to probation.
Rivera died of a heart attack. He sat motionless in a chair for nearly an hour before hospital staff checked on him.
Another suspect, 41-year-old Martin Smith, has already pleaded guilty. A third suspect, 44-year-old Richard Alten, did not appear for a hearing Thursday. A warrant has been issued for his arrest.