Ken Thompson searched intensively. In 2010 he quit his job, set up a “Find Andrew” website, and cycled roughly 6,500 km through multiple European countries (including the UK, Belgium, France, Luxembourg, Netherlands, Germany, Poland, and Czech Republic) to generate publicity and leads.
How he was foundIn September 2010 (after about 2½ years), a tip from a Dutch woman in Amsterdam proved decisive. She became suspicious about comments regarding the boy (then about 6) and his “mother,” searched online for missing Australian children, found Ken’s website, and alerted authorities. Dutch police located Andrew (who was living under a different name, spoke fluent Dutch, and had been enrolled in school) and placed him in the care of the Netherlands’ Child Protection Service. Melinda Stratton was arrested and faced extradition proceedings to Australia on contempt/custody-related charges.
Ken arrived in Amsterdam and was reunited with Andrew at a child-protection facility (with psychologists present). He recognized his son immediately (noting details like a gap in his teeth and smile). Andrew knew Ken was his father but did not fully recognize him after the long separation; the reunion was carefully managed. Legal processes under the Hague Convention on international child abduction were used to facilitate Andrew’s return to Australia.
This is widely reported as a successful reunion after a high-profile parental abduction and international search.Note: Other cases involving people named Andrew Thompson exist (e.g., the unsolved 1996 disappearance of a child from the Thompson family in Chicago, Illinois, linked to a relative’s suspected involvement; various criminal cases). The Australian abduction/reunion is the one that best fits the “found after years” theme of your prior questions.