There are fresh calls for probes into alleged atrocities in South Sudan, where both government and rebel forces have been accused of human rights abuses.
In a statement Thursday, Human Rights Watch said "horrendous crimes" have been committed across the country.
The rights group said a "thorough, impartial investigation" could help troubled South Sudan "break with the past and begin a healing process."
Human Rights Watch researcher Skye Wheeler spent three days over the past week in South Sudan.
Wheeler tells VOA she saw looted and burned homes and what appeared to be victims of ethnically targeted killings at a hospital, church and homes in Bor, the capital of Jonglei state.
"You walk in and there is a woman on the ground and then further on, deeper in, I saw three other women around a house who had been shot and killed," Wheeler said. "Their bodies were in a state of some decay. Another room had six women, shot, who had been lying around in different parts of the room and perhaps, most poignantly of all, there was another hut," she continued. "And, you opened the door and your could barely see inside. The smell of decay was very, very strong. And, all you could see was the hand of a woman who had hidden under the bed before she was killed."
In New York Thursday, U.N. spokesman Farhan Haq said the world body was collecting evidence of human rights violations in Bor and in the capital, Juba.
In another development, Anglican Archbishop Justin Welby held talks with South Sudan's President Salva Kiir on Thursday.
The archbishop called for an investigation into reports of targeted killings of Christian aid workers.
"I've heard particularly bad news of attacks on people, Christian people working as Christians in hospitals and that is a great, great concern, and what is important is that over time, through the agency of the people involved in the cessation of hostilities, that the facts behind this are established in a way that nobody can deny anyway, and that we understand fully and lessons are learnt. There must be no impunity," the archbishop said.
South Sudan erupted in unrest after President Salva Kiir accused his former vice president, Riek Machar, of attempting a coup -- a charge Machar has denied.
Thousands of people are believed to have died in the ensuing violence -- some in clashes between the army and rebel forces, others in targeted ethnic violence.
The U.N. humanitarian office says more than a half-million people have been internally displace since the unrest erupted in mid-December. It says more than 100,000 people have fled to neighboring countries.
A woman identified as Najabi, one of many refugees at a camp near the border with Sudan, said violent clashes between government and rebels forced her family to flee on foot from the Upper Nile State region.
"We walked for seven days with my six children," she said.
Last Thursday, representatives for South Sudan's government and the rebels signed a cease-fire agreement in Ethiopia. However, both sides have accused the other of violating the agreement.