Five years ago this week, Altona bookshop owner Jill Brookes was bashed and left for dead in the aisle of her Harrington Square store.

Despite a $100,000 reward for information offered by Victoria Police, her near-fatal bashing remains unsolved.

Ms Brookes, then aged 61, was discovered by a fellow trader about 5pm on July 20, 2012, in a pool of blood inside West Side Stories, now a laundrette.

The attack has left her with severe brain damage and unable to properly communicate.

Detective Senior Constable Matt Noonan said Ms Brookes was in a high-care facility.

“Certainly, she requires 24-hour-a-day care, most likely for the rest of her life,” he said.

“Her quality of life has been affected significantly.”

Police were hampered by the crime scene being covered in customers’ fingerprints, contaminating it with too much DNA.

Investigators are still interested in speaking to the owner of a white tray truck seen in a rear lane off Harrington Square.

On May 21, 2013, a letter was dropped into Altona North police station containing news clippings from the Weekly and a “somewhat cryptic” message from cut-out letters.

A second letter addressed to Altona police, again with letters cut from the Weekly, was placed in the letterbox of an Altona home on July 2, 2013. It contained a sum of money.

“Clearly somebody knows something and they’re reluctant to come forward, but we’re hopeful that even given the time delay in that it’s been five years, that somebody will do the right thing and come forward and assist us,” Detective Senior Constable Noonan said.

“We’d be appreciative of any information, as little as it seems or as big as seems – anything that’s brought forward gets looked at and might assist us greatly.

“I guess it is a frustration for us that we’ve never been able to identify who that person is.

“It would be nice to have some closure for the family, to be able to have some sort of idea as to what took place on that day.”

Anyone with information should call Crime Stoppers on 1800 333 000.