Stephanie Scott's alleged killer 'sent twin brother her engagement ring in the post'

Stephanie Scott’s accused rapist and murderer sent his twin brother the NSW school teacher’s engagement ring in the mail, a court has heard.

Marcus Stanford, 24, pleaded guilty at the Griffith Local Court on Thursday to being an accessory to the murder of Ms Scott.

Marcus's identical twin brother, Vincent Stanford, 24, was charged with sexually assaulting and murdering Ms Scott in the New South Wales town of Leeton in April, 2015.

The police charge sheet said Marcus "did assist" in the murder and he received the engagement ring in South Australia via the post, Fairfax reports.

Vincent, who also appeared in the Griffith Local Court via video link, was ordered to stand trial for the murder in the NSW Supreme Court.

His solicitor David Davidge requested to have it adjourned to allow time for his client to be assessed to see if he is fit to stand trial, but the court rejected his request.

Vincent is scheduled to appear in court again on May 6.

Marcus has been pledged for sentencing and his case will mentioned again on May 2.

Ms Scott was an English and drama teacher at Leeton High School who was last seen planning lessons before she was killed, just days before her wedding.

Police allege she was murdered in the early afternoon of April 5 by Vincent.

Her body was found five days later in Cocoparra National Park, and area where it is understood the Stanford family camped often.