Cold case detectives have had a major breakthrough in the suspected murder of Krystal Fraser, who was just three days away from giving birth when she disappeared on a cold winter's night almost a decade ago.

Krystal Fraser was last seen in Pyramid Hill 2009. Credit:Victoria Police

On Tuesday, missing persons squad detectives arrested a 61-year-old man from the tiny town of Pyramid Hill, north of Bendigo, as part of their investigation into Ms Fraser's disappearance.

He was interviewed by police and has been released pending further inquiries.

Ms Fraser was 23 and heavily pregnant when she vanished from Pyramid Hill in June 2009.