Police are investigating an allegation of fraud at Café Britannia and have quizzed a man.
The café, which ran from a building attached to Norwich Prison, announced on Wednesday it was closing on Friday.
The closure came after the Ministry of Justice, which owns the site, served a notice to management saying they needed to leave.
On Thursday a Norfolk police spokesman confirmed to this newspaper that it had an ongoing accounting fraud investigation relating to Café Britannia dating to 2018.
A man in his 60s has been interviewed under caution and released under investigation, the spokesman added.
More than 50 people are set to lose their jobs with the closure of the café.
The café is run by community interest company Britannia Enterprises Norwich CIC.
The MoJ declined to comment.
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