A South Sudanese man casts his vote in a ballot box while carrying his child at a polling center during the third day of the South Sudan independence referendum in the city of Um Durman, Sudan, on Jan. 11. Thousands of people began casting ballots on Jan. 9 during a week-long vote. The mainly Christian south is expected to secede from the primarily Muslim north. Nasser Nasser/AP
South Sudanese men wait to casts their vote at a polling station in Juba, South Sudan, on Jan. 10. Jerome Delay/AP
A South Sudanese woman waits to cast her vote at a polling station in the small rural village of Peiti, South Sudan, on Jan. 9. Jerome Delay/AP
A South Sudanese woman casts her vote at a polling center in Juba, South Sudan, on Jan. 10. Pete Muller/AP
A polling center official explains to a South Sudanese woman the two voting signs contained in the ballot, separation and unity, at a polling center during the third day of the referendum in Um Durman, Sudan, on Jan. 11. Nasser Nasser/AP
Daniel Chol looks around as his mother, Josephena Thal, prepares her ballot in a referendum vote at St. James Catholic Church in Glendale, Ariz., on Jan. 9. The polling place in Glendale was one of only eight in the entire US. David Wallace/The Arizona Republic/AP
South Sudanese who have returned to South Sudan on barges stand on the banks of the Nile river in Juba's port on Jan. 10. Jerome Delay/AP
A member of Sudan People's Liberation Movement (SPLM) sits at a checkpoint in south Kordofan, South Sudan, on Jan. 11. SPLM, the former southern rebel, now rules a semi-autonomous authority in the southern capital of Juba. Zohra Bensemra/Reuters
South Sudanese occupy a barge on which they have returned to South Sudan in Juba's port on Jan. 11. Jerome Delay/AP
South Sudanese children who have returned to South Sudan by barge sit amidst their belongings in Juba's port on Jan. 10. Jerome Delay/AP
South Sudanese children dressed in their Sunday best, who returned to South Sudan by barges on the Nile river, sit in Juba's port on Jan. 11. Jerome Delay/AP
A South Sudanese woman carrying her child stands at her home in south Kordofan, South Sudan, on Jan. 11. Zohra Bensemra /Reuters
One Moscow TV station has video that reportedly shows Nemtsov and a woman walking across a bridge shortly before he was killed.
ByLaura Mills, Associated Press
The investigation into the killing of Boris Nemtsov, a fierce critic of Russian President Vladimir Putin who was gunned down not far from the Kremlin, faced conflicting reports Monday about possible surveillance footage of his slaying.