SW have a tracing facility based in their offices in either Sligo or Letterkenny. They use the PPSN to search their records. They connected me with an old insurance policy I'd forgotten about (mega-bucks!!). The searcher contacts SW. They search their records and write to the "missing" person supplying contact details. SW then bow out.
If he is genuinely missing have the Guards, employers, former addresses (for a forwarding address) in-laws ever been been contacted?