Sentencing is Aug. 6. Williams faces a maximum life prison term.
Williams was caught last month in Rosebud, about 35 miles south of Waco.
Freddy Lee Foots was arrested days after the Sept. 5, 2007, holdup following a a chase that ended in Van Horn. More than $500,000 was recovered.
Foots was convicted and in October sentenced to nearly 30 years in prison.
Both 53-year-old men had served time for a 1988 Dallas armored car robbery.
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