He was later reburied at Mt Eden Prison and again in October 1989 at Waiaua Marae.
As a result of the murder, the Government sent troops to Opotiki. The Mokomoko whanau was reduced to just 30 women and children and 70,000ha of land were confiscated.
In 1988, Mokomoko's co-accused were granted a statutory pardon as part of the Ngati Awa settlement legislation.
The pardon restored the "character, mana and reputation" of the accused, their whanau and their iwi.
In 1992, without consultation with his descendants, Mokomoko was granted a posthumous free pardon by the Governor-General but it failed to restore the chief's character, mana and reputation.
Dr Sharples said that by those actions, the Crown had perpetuated the shame and stigma carried by the whanau of Mokomoko.
"I want to apologise to the whanau and express sincere regret for the way the Crown has acted in the past."
He acknowledged that yesterday's signing was only a "small step" for the Mokomoko family in seeking justice, and said he would continue to work to have the legislation introduced to Parliament.
Family spokeswoman Karen Mokomoko described the agreement and the proposed legislation as a "significant step in the healing process for the whanau".
"Sadly, many who began this journey of clearing the name of our tupuna are no longer with us ...
"However, we believe that in taking this step our rangatira and those who have passed since will finally be able to rest in peace."
- APNZ