delete records from uploads and associated images

I am building a Contest for Artists app. There is a charge for the contest entry so I am utilizing the shopping cart plugin and customizing it myself. Everything is working as expected by I have one minor housekeeping issue.

If the Entry is not paid for, the cart_item record is automatically deleted by the cart after 24 hours which is fine. I have the contest_entry record deleting automatically as well. What I would like to do is also delete the associated _upload record and its files from the server.

I know that if I delete the contest_entry record through the administrator that the _upload record and the files including thumbs are deleted.

Is there a function call I can hook into to perform this operation or any other suggestions are welcome.