Mr Brown said Mason's guilty pleas had come as a "huge relief" to him, his family and extended family members.
Mr Brown wished to thank those who had given him and his family tremendous support "throughout this difficult time".
Kate Brown said the pleas came as a "great relief" to her and her family and she was "very appreciative" of the hard work of police and Victim Support, and the community support and assistance her family had received "through this ordeal".
Officer-in-charge Detective Sergeant Pete Blackwell was also relieved guilty pleas had finally come, given the "overwhelming evidence".
"It is a relief we all share for the Brown family as the guilty pleas also mean they have avoided the added trauma of having to come to court to give evidence against him at a trial."
Mason, of Ngati Ranginui iwi, originally appeared in the High Court to challenge the jurisdiction of the court to try him. Mason made an application to be dealt with in accordance with the tikanga Maori jurisprudence process.
His assigned amicus curiae lawyer Annette Sykes acknowledged to Justice Heath it would have been a "bold decision" to rule in Mason's favour but she urged the justice to give Mason the opportunity to explore the issue under the jurisdiction of the customary law process. Maori lawyer and constitutional expert Moana Jackson also appeared in court to give a submission in support of Mason's application.
Justice Paul Heath ruled the court did have jurisdiction but told Mason the exact reasons for his ruling would be delivered in writing as soon as possible.
Following the oral ruling, Mason and Ms Sykes indicated he would plead guilty.
The court briefly adjourned as paperwork was prepared. When court resumed, Mason pleaded guilty to both counts and was remanded in custody pending sentencing on July 27.
The judge ordered some suppressions around coverage of the case but for the first time most of the story of the killing can now be told.
The horrific details of what happened the night Sandra Brown died can be read in today's Bay of Plenty Times.