The Buchanan County Prosecutor's office charged Tony King, 29, of Bethany, Tuesday with second degree murder in the death of his cellmate Michael Bozarth, 25.
According to court documents, King strangled Bozarth in their cell between the night of June 10 and the morning of June 11.
Workers at the Buchanan County jail found Bozarth in the cell after hearing commotion from other inmates. King and Bozarth were the sole occupants of the cell.
King was scheduled to be sentenced this month in the death of his 7-year-old son.
Authorities have offered no motive for why he allegedly killed Bozarth.
Bozarth, a registered sex offender, was serving time for statutory sodomy.