With newspapers you would need to access them perhaps via the local library where he died? Do you have any clue as to where he died? The suggestion is around 1997/98 so that would be a starting point for searching the papers.
Another alternative is to write to a suitable newspaper appealing for information.
I see that you posted on the topic that I flagged up. If Lee or Lochrane still have active email addys, then they would be notified of activity on that topic.
In some ways you are looking for a needle in a haystack

Try and get as much information as you can from your mum.