Kyran Durnin was reported missing from his home in Drogheda, County Louth, in August 2024.
Five people had to be rescued from the building on 31 October including four children.
Gardaí commenced an investigation into the alleged attempted arson of the property in Drogheda, County Louth.
An Garda Síochána said "this was an extremely dangerous act endangering the lives of the residents".
The Irish Premier Division club were expelled by Uefa under a rule which states two clubs in the same competition cannot be under the same ownership.
Gardaí searched a business in Drogheda and two residential properties in Drogheda and north Dublin on Wednesday.
It is part of the investigation into the murder of Kyran Durnin who disappeared more than two years ago.
Kyran Durnin was reported missing at the end of last summer but police believe he may have been killed more than two years earlier.
Nine properties in Drogheda were searched by Irish police on Tuesday morning.
