Southern Highlands Provincial Police Commander, Chief Superintendent Martin Lakari confirms this afternoon.
He said the suspects, including the deceased's husband and his two accomplices are being detained at the Mt Hagen police cells in Western Highlands Province.
Police investigations are continuing.
PPC Lakari also confirmed that the relatives of the deceased had staged a peaceful march in Mendi town as a sign of sorrow.
They want the law to take its full force and will refuse any compensation.
It is alleged that the deceased was murdered by her husband in Mendi town and was wrapped in a canvas and driven to Wara Kagul in the hope to ditch the body.
However, police at the check-point intervened and found the body at the back of the vehicle.