The Regional Assistance Mission to the Solomon Islands or Ramsi, says two alleged former Guadalcanal Liberation Force members have been arrested on charges related to a murder on the Weathercoast of Guadalcanal.
Francis Lela and a male juvenile gave themselves up along with two other men to Ramsi and Royal Solomon Islands Police investigators at Kolina.
The four have been assisting Ramsi police with their enquiries.
In another investigation, Ramsi police have arrested Moses Su'u, an alleged former Malaita Eagle Force member.
He has been charged with the abduction of a man in Mount Austen in September 2001.
Our correspondent in Honiara says the charge relates to the disappearance and susequent murder of Selwyn Saki, a former Supreme Commander of the rival Guadalcanal-based Isatabu Freedom Movement.
Ramsi police say investigations into both crimes are continuing.