Gardai in Longford are examining CCTV footage of the Athlone road area following a series of suspected arson attacks on Sunday evening.
The first incident occurred at a residence on the Athone road at approximately 8.55pm; no occupants were in the house at the time.
It followed reports of a fire at the same property earlier that evening at half-past six, when fire services were called to bring a blaze under control.
A technical examination of the property was carried out and gardai are examining CCTV footage of the area from that evening.
Gardai are also investigating a fire at a derelict residence on the Battery Road, just after twenty past 10 on Sunday night.
Emergency services attended the scene and extinguished the blaze.
There were no injuries reported and investigations are ongoing.