The prime suspect in one of the most infamous unsolved killings in Victorian history has landed back in Australia and will soon be charged with the 1977 Easey Street murders of Suzanne Armstrong and Susan Bartlett.

Perry Kouroumblis, a 65-year-old dual citizen of Australia and Greece, landed at Melbourne Airport at 11.32pm on Tuesday after a two-leg flight from Rome flanked by homicide detectives.

Victoria Police said he would be interviewed later on Wednesday and subsequently face Melbourne Magistrates’ Court.

“The man will formally be charged with two counts of murder and one count of rape during this court appearance,” police said in a statement released about 2am on Wednesday.

Kouroumblis – who was aged 17 when Armstrong, 27, and Bartlett, 28, were found stabbed to death in their Collingwood home almost 50 years ago – maintains his innocence.

The decades-old Easey Street cold case burst back into the headlines in September when Italian authorities arrested Kouroumblis at Rome’s airport on an Interpol notice. Within days, he agreed to be extradited to Australia, marking a major milestone for Victoria Police in one of their highest-priority cases ever.

Dean Thomas, the head of the homicide squad, sat one row in front of Kouroumblis on the Airbus A350 flight that left Rome about 1am AEST on Tuesday and landed in Doha about 6am. After 10am, the travelling party departed on a 13-hour Qatar Airways flight to Melbourne.

At Tullamarine Airport shortly before midnight, a handful of media watched the Boeing 777 land after an approach from the north.