The man arrested after the attack on independent MP Helen Haines can be revealed as Brendan Nugent.
The 43-year-old has been in custody since being arrested yesterday afternoon and has spent this morning being questioned by detectives.
A source with close knowledge of the investigation told the ABC that Mr Nugent was known to police.
It is understood he has undergone a mental health assessment.
Ms Haines, 65, who has represented the people of Indi since 2019, suffered critical injuries and remains in hospital in Melbourne.
She was retrieving items from the boot of her vehicle at the time of the alleged attack.