Divers searching small ponds near where 30-year-old Dara Lee Watson and her former fiancée lived found the phone Thursday.
Investigators think the phone was used Feb. 8 by David Hedrick to mislead the woman’s family and employer about her safety. Text messages said Watson was fine.
Officials say someone who gave Hedrick a ride from the woods saw him walking with a shovel.
Hedrick shot himself to death Feb. 10 in their home. Watson was last seen Feb. 6. Her burned car was found Feb. 7 in the Francis Marion National Forest.
A candlelight vigil was planned Friday night in Mount Pleasant Memorial Waterfront Park across the Cooper River from Charleston.