Two people are facing charges in the case of a 48-year-old Six Nations man missing since June.
OPP, who are conducting a joint investigation with the Six Nations Police Service, say Douglas Hill was last seen on the Six Nations of the Grand River reserve on June 24.
They say the investigation led them to reclassify Hill's disappearance as a homicide, though they offered no details as to what led them to that conclusion.
Police say a 35-year-old woman from Brantford has been charged with one count of accessory after the fact to murder and will appear in court at a later date.
A 17-year-old girl was arrested Wednesday and charged with second-degree murder.
Police did not indicate whether Hill and the accused were known to each other.
Investigators say tips from the community helped lead to the arrests, but they are asking anyone with information about the case to come forward.