Those issues may be addressed in upcoming talks, according to South Sudan's spokesman Atif Kiir.

CNN: Sudan and South Sudan sign partial agreement

The last letter Mercer received from his daughter said she expressed "disappointment and dismay" that they had not heard from their Pakistani-based lawyer, Atif Ali Khan, in three weeks.

CNN: Taliban move detained Western aid workers

"We were left with no choice but to suspend our direct bilateral talks with Sudan, " said Atif Kiir, the spokesman for Juba's delegation at the talks in Addis Ababa.

BBC: South Sudan scraps direct border talks with Khartoum

Associated Press writers Munir Ahmed and Zarar Khan in Islamabad, Atif Raza in Karachi, Riaz Khan in Peshawar, Rasool Dawar in Mir Ali, Anwarullah Khan in Khar, Abdul Sattar in Quetta, Matiullah Achakzai in Chaman, and Asif Shahzad in Lahore contributed to this report.

NPR: Former Pakistani Prime Minister Declares Victory