Stephen Williams, Karen's brother, has claimed he's one step closer to justice.
53-year-old Borce was arrested by detectives from the Missing Person's Squad on Wednesday morning, nearly 18 months after Karen's disappearance.
When asked about the arrest, Williams said he had been 'waiting patiently' for charges to be laid over his sister's death.
'Today has been a surprisingly emotional day - one which I have been patiently waiting for,' Mr Williams said in a statement.
'It is in no way a celebration, it's another stage in bringing my beautiful sister Karen the justice she so deserves.
'A huge thank you to the Missing Persons Squad - also to Emily, Lachlan, my cousins and work colleagues who have been very supportive through these long last 18 months,' Williams finished.
Rob Stary, Borce's lawyer, said that they would be pleading not guilty.
Borce will remain behind bars until his trial early next year.