While searching, take the time to go to the Dell Website, and change the ownership to you. There is a form you must fill out, and they must verify you and your address, phone, email, etc.... and you must wait about 21 days, on average.
Then you can contact them again as owner... You do not need to know the previous owner. You can even download the invoice (without the owner name) and the date it was purchased.
Within 30 days, part of your problems are solved...
But if you are not the legal owner, Dell then has your address for the authorities, and somebody from your county sheriff office will be by to see you.
You can find it by searching for change of address form, or change of ownership form.