Roberta Williams, the former wife of slain underworld figure Carl Williams, has been arrested in Melbourne.

Key points: Ms Williams was arrested at a home in Strathmore, in Melbourne's north

Ms Williams was arrested at a home in Strathmore, in Melbourne's north Three men, all in their 20s, were arrested elsewhere as part of the same investigation

Three men, all in their 20s, were arrested elsewhere as part of the same investigation The Fraud and Extortion Squad are investigating allegations of false imprisonment and extortion with threats to kill

In Channel Nine footage, Ms Williams can be seen being led from a home in handcuffs and placed in an unmarked police car before being driven away.

A Victoria Police spokeswoman said a 50-year-old Strathmore woman had been arrested as part of an investigation into allegations of false imprisonment and extortion with threats to kill.

The Fraud and Extortion Squad executed five warrants this morning at addresses in Craigieburn, Greensborough and Strathmore.

Two Greensborough men, aged 24 and 27, and a 24-year-old Craigieburn man were also arrested and were assisting police with their enquiries.

Ms Williams is the former wife of drug boss and convicted murderer Carl Williams, who was bashed to death inside Barwon Prison in 2010.

The Age last month reported allegations Ms Williams imprisoned and assaulted the producer of her proposed reality TV show.

It reported the allegation that Ms Williams and five others attacked the man in a Collingwood building and demanded money.

The producer reportedly said the gang forced him at gunpoint to ask relatives to transfer $17,000 to a bank account before demanding further payments.

Roberta Williams was arrested at her Strathmore home this morning. ( AAP Image: Joe Castro, file photo )

Victoria Police last month charged a 36-year-old man, reportedly a cameraman on the program, with false imprisonment, threats to kill and assault over an incident in Collingwood on July 9.

A GoFundMe page has been set up with the goal of raising $50,000 for Ms Williams's reality TV project.

The page says the series will be "a mixture of Mob-Wives meets Keeping up with the Kardashians".

"However, it will have it's [sic] own unique format, never before seen in an Aussie series," the page says.

By this morning it had raised $865.

The police investigation is ongoing.