I lost my dog a couple days ago, this women brought him in today, 4-2-18, and I was wondering if it was free to get him back because he’s mine and it was an accident for him being there?

But they will require proof that your baby belongs to you also If you have located your pet on our website, write down the ID number and bring it to the shelter to present to the service representative at the front desk. If you are visiting the shelter to do your search, you MUST have your ID to show before being escorted to the kennels to view animals.  You will not be allowed in the kennel without ID (passport, driver's license, student ID)

I don't know if they will charge you. I would contact them immediately.