Slade, Brown's grandnephew, is a codefendant in the $6.7 million charter fraud case. Bellwoar is Slade's lawyer.
Mena said she joined Lab's board in January 2010 after learning about the vacancy from Slade. She left in September.
The validity of Slade's background check was among issues that surfaced in 2012 when the district was reviewing Lab's operations as part of the renewal of its operating charter.
The district's Office of Inspector General investigated when auditors said it appeared that Slade's birth date and Social Security number had been altered on clearance documents he provided. During a district interview, Slade denied submitting a falsified record.
In court Wednesday, Mena told Assistant U.S. Attorney Joan E. Burnes that Slade and others assured her that Slade had told the prior board about his record in 2009.
Mena said she never checked board minutes to verify Slade's account. And despite the district information, Mena said, the board had not considered rescinding a recent pay increase that had boosted Slade's salary to $168,000 because the prior board had dealt with the issue.
Lab's charter renewal is pending.
Also Wednesday, Brown's defense attorneys presented testimony from several parents and others who praised Brown's work ethic and lauded the academics of the three small K-8 charter schools she founded in the city.
"It was like getting a private school for free," said Donna Carrington, whose daughter began at Laboratory in second grade and now attends the High School for Creative and Performing Arts, a district magnet school.
Brown is charged with defrauding the charters and conspiring with Slade and another former administrator to obstruct justice by orchestrating a cover-up.
The trial resumes Thursday.