It was his first day back since he was rushed to the hospital complaining of chest pains Wednesday.
Bell's financial administrator, Lourdes Garcia, took the stand, saying Rizzo personally authorized dozens of loans adding up to almost $2 million.
Garcia said he was making more than $1 million per year. Garcia saw the documents and wrote the checks.
The Los Angeles District Attorney's Office says most of the loans were to city employees and city council members.
The only collateral were vacation days and sick pay.
Rizzo's attorney doesn't deny his client authorized the loans, but claims they were for legitimate reasons and were legal.
The district attorney's office says Rizzo, 57, didn't have the authority to do so and faces 54 felony counts for corruption.
Former Bell City Councilman Luis Artiga received one of the Bell city loans, but denies it was done illegally.