A fence between two Dandenong homes was smouldering for up to two hours before CFA crews were called to extinguish the fire.
Greater Dandenong CIU Detective Senior Constable Tony Lavars said the fence on Belfort Street appeared to have been set alight.
Police and Dandenong CFA attended about 10.30pm on 17 March.
The fire caused only minor damage and did not spread to the adjoining homes.
Det Sen Const Lavars appealed for anyone with information to call Crime Stoppers on 1800 333 000.
