My question involves criminal law for the state of: CA

We are a company that had a former employee steal about 63K in funds by purposefully re-applying for reimbursements twice for the same items, on one occassion, three times and applying for reimbursements that were from invoices the former employee never paid.

The detective investigating said that we must prove that the former employee had intent to steal, as well as the theft. We have absolute proof funds (and duplicate funds, if you will) were deposited to the former employee's bank account and corresponding paperwork the former employee submitted. My question is why do we have to prove intent? Is it not enough that we prove this person received the illicit funds?