A mysterious letter dropped in a police mail box in western Melbourne may hold the key to solving a vicious attack on bookshop owner last year.
Jill Brookes, 62, was attacked inside her store in Harrington Square at Altona.
She suffered extensive brain damage and police say her condition has not improved much over the past year.
A letter, written using letters cut out of a newspaper, was handed in the Altona North police station in May.
Detective Senior Constable Matt Noonan says the man who delivered the letter may be the key to the investigation.
"The person who dropped the letter into the police station had some information that makes us believe he has the key to identifying and locating the offender," he said.
"There's somebody out there who knows something and we want to find out what they know."
Police have security camera footage of the man delivering the letter but say it has not helped them identify him.
Ms Brookes's husband Michael Overend has made an emotional plea for anyone with information about the attack to come forward.
"It has completely destroyed both Jill and my life, I would dearly love to have the person caught," he said.
"It would give me some peace but I will always have to live with the fact that I'll never have my wife back with me.
"She'll never come home, she'll live in some sort of institution for the rest of her life." Mr Overend said.