Now, what allegedly happened at Warrawong McDonald's on February 22 has been revealed via police documents in Wollongong Local Court.

According to police, Deanna Struber placed an order using the drive-thru about 5.20pm. She then moved her Nissan X-Trail, which had her two young sons inside, forward to the serving window to pay.

However, Ms Struber appeared to forget something and began reversing her car.

Behind her, was a Ford ute with a couple and their six-week-old baby inside. They also wanted to order food.

The pair watched as Struber's car allegedly reversed towards them; the passenger leaning over to toot the horn, fearing their vehicle was about to be hit.

Read more: How accused car bomber tracked down couple who beeped at Macca's Warrawong

Police say Struber then stuck her head out the window and verbally abused the couple, before driving off.

The couple followed Struber and both vehicles drove away.

The police account of what happened next outlines conflicting versions of events.

However, what is clear is the incident sparked a month-long investigation by the Fixated Persons Investigation Unit (FPIU).

The FPIU was set up by NSW Police Commissioner Mick Fuller in 2017 to investigate those who are seemingly fixated on individuals, institutions or issues but are not considered a risk for terrorism.

Struber, 31, was charged with accessory after the fact to destroying or damaging property and stalk/intimidate, and given bail.

Her partner, 33-year-old Ryan Sharp, was charged with two counts of using a carriage service to threaten serious harm, two counts of stalk/intimidate, using a carriage service to threaten to kill, destroying or damaging property, placing an explosive in/near a vehicle, threatening a witness and two counts of possessing or using a prohibited weapon.

The pair return to Wollongong Local Court on May 22.