Did you win the item at auction?

They may not have been happy with the price so using excuses.

They can not cancel the transaction without you agreeing to it so if they send the request to mutually cancel decline it.

You can leave neg feedback to let others know of the problem.

If the death was genuine then I guess ebay would be the last thing on their mind so look and see if they have left feedback in the time you have been waiting or done listings.

Look for any activity on their account.

If there is none they might be genuine but in the end there is nothing you can really do if they do not want to send it.