[California]Ex-employee locked work files

Hi All,

I'll try to keep this short. One of my coworkers quit her job at the accounting firm where I work because she was unhappy with the job.

After reassigning her projects, it was discovered that a number of documents the coworker had put together have been password protected. Said coworker has refused to provide the password to access the files, and now avoiding attempts to contact her. Management says they want to take legal action as the documents were generated on company property with company computers.

I spoke with her out of work, off the record -We're in the same social circle- and her argument is that she created these documents on her own and isn't required to release them. I'm playing devil's advocate wondering which side is correct. Can the company take legal action against her?

TL:DR Co-worker quit her job. Password protected files were found on her computer. She won't provide the password. Management wants to take legal action.