SA man arrested over Stephanie Scott killing

The identical twin brother of Stephanie Scott's alleged murder has been arrested in South Australia in connection with the killing.

Marcus Stanford, 24, is expected to be charged with being an accessory after the fact, meaning he was allegedly involved after the Leeton school teacher was killed.

The young man was arrested at 6.55am AEST this morning at a home in Forreston, west of Adelaide.

Stanford will appear before Mount Barker Magistrates Court today where NSW Police will ask for him to be extradited to NSW.

Ms Scott was reported missing after disappearing from Leeton High School on Sunday April 5, a week before she was due to get married.

School cleaner Vincent Stanford was arrested on Wednesday April 8, and was later charged with murder and aggravated sexual assault.

Ms Scott's burned remains were found at a nearby national park.