Also managed to work out that Highlander cannot be the normal cop so he must be paranoid, insane or mafia. i.e. if Tom is normal and treva is mafia and therefore all other players are town.
Highlander --> Treva (mafia) - Normal
Hedger --> MaD (mafia) - Insane/Paranoid
ARay --> MaD (town) - Normal/Naive
MaD --> Tom (town) - Normal/Naive
Therefore impossible so Tom cannot be normal. Treva can still be mafia though as Tom could be paranoid and anyone would turn up mafia.
So Tom shouldn't actually investigate me tonight as it won't narrow down his results. He should probably investigate MaD or ARay.