Melbourne's gangland struggle is intensifying once again.

On Monday Des "Tuppence" Moran was gunned down in broad daylight.

Yesterday, his sister-in-law Judy Moran was revealed as one of three people charged in relation to the execution. Today, her house has been the subject of an arson attack.

Bob Undy from the Melbourne fire bureau says it has left a damage bill of AU$150,000.

"It's definitely suspicious and the police are looking into it."

Judy Moran was not home as she spent the night behind bars, after being charged with being an accessory over the murder of Tuppence. A court has been told she dumped the suspected getaway car and was overheard talking about disposing of items used in the killing.

Suzanne Kane is also charged with being an accessory, while her de facto Geoffrey Amour has been charged with murder.