Police and correctional officers often quote witnesses and suspects word-for-word in their reports–causing problems if you’re unsure about the punctuation.
Here’s the rule: Commas and periods always go inside quotation marks. In the US, there are no exceptions. (Canada and the United Kingdom do it differently.)
Here are a few examples:
Lewis replied, “I never touched her.” CORRECT
Inmate Yan told me, “I work for the chaplain,” when I asked why he was in the building. CORRECT
“This will never work,” said Commissioner Ryan. CORRECT