Akech Arol Deng has not seen his wife and son since they were seized by Arab militias from their home in south Sudan 19 years ago.
His son, Deng, was just three years old at the time but Mr Arol is sure they are still alive, being used as slaves in the north.
"I miss them so much. I really hope that one day they come back," Mr Arol told the BBC News website mournfully in his home of Malualbai, just a few hours' on horseback from the Bahr el-Arab river which divides Muslim northern Sudan from the Christian and Animist south.
It's like I was still in the camp, it's the same situation as in the north
Some 8,000 people are believed to be living in slavery in Sudan, 200 years after Britain banned the Atlantic slave trade and 153 years after it also tried to abolish slavery in Sudan.
But rows about money mean no-one is doing anything to free them.
In the same year that Mr Arol's family was kidnapped, Arek Anyiel Deng, aged about 10, was seized from her home, not far from Malualbai.
Arab militias rode in to her village on horseback, firing their guns. When the adults fled, the children and cattle were rounded up and made to walk north for five days before they were divided between members of the raiding party.
Forced conversions
Ms Anyiel returned home under a government scheme last year.
"My abductor told me that I was his slave and I had to do all the work he told me to - fetching water and firewood, looking after animals and farming," she said.
"When I was 12, he said he wanted to sleep with me. I could not refuse because I was a slave, I had to do everything he wanted, or he could have killed me."
Such raids were a common feature of Sudan's 21-year north-south war, which ended in 2005.
The northern government is widely believed to have armed the Arab militias in order to terrorise the southern population and distract rebel forces from attacking government targets.
According to a study by the Kenya-based Rift Valley Institute, some 11,000 young boys and girls were seized and taken across the internal border - many to the states of South Darfur and West Kordofan.
The boys generally looked after cattle, while the girls mostly did domestic chores before being "married", often as young as 12.
Most were forcibly converted to Islam, given Muslim names and told not to speak their mother tongue.
War of words
Sudan's government has always rejected claims that people are living in slavery but admits that thousands were abducted during the war. It says this is an ancient tradition of hostage-taking by rival ethnic groups.
One senior government official strenuously denied there was any slavery in Sudan but bizarrely acknowledged: "It was the same as when people were taken from West Africa to America."
With peace, I thought they would be freed by now
The United Nations defines slavery as: "The status or condition of a person over whom any or all of the powers attaching to the right of ownership are exercised."
Ms Anyiel and several others we spoke to certainly seemed to have been living in conditions of slavery - having been abducted, subjected to forced labour and often beaten.
To be able to work with the return programme the government set up in 1999 under intense international pressure, donors agreed to use the euphemism "abductee".
About 3,000 were taken back home before the programme ran out of money in 2005.
Donors pulled out, saying some were not genuine slaves, some had been returned against their will and had been left to fend for themselves in the desolate, under-developed south.
The government then funded the return for a while but strangely, the end of the war seems to have taken the urgency out of the project.
The governments in both north and the autonomous south seem more interested in spending their new oil wealth.
Officials from both administrations say they are still working out their new policy on the "abductee file".
Disillusioned
Ahmed Mufti from the government's Committee for the Eradication of Abduction of Women and Children (CEAWC) says the Arab tribal leaders are now more than happy to release the "abductees" but his group does not have the $3m he estimates it would need to arrange transport and pay officials to organise the operation.
Faced with this lack of progress, James Aguer, the man at the forefront of the campaign to free Sudan's slaves, is becoming increasingly disillusioned after spending some 20 years risking his life for the cause.
"With peace, I thought they would be freed by now," he says bitterly.
He says he has the names and location of 8,000 people, who could easily be freed from the Arab cattle camps, as soon as the political will is there.
He says the true number of those being forced to work against their will without pay in Sudan is more than 200,000, although most donors believe that is an exaggeration.
Sitting on the dusty ground outside the abandoned mud hut where she and her five children now live, Ms Anyiel is delighted to have finally gained her freedom and to be able to make decisions about her own life.
But freedom is not necessarily easy - she now has to support the children on her own, with no assistance from donors or the government.
Her only income comes from collecting firewood in the bush to sell in the local market.
"It's like I was still in the camp, it's the same situation as in the north," she complains.
Tribal markings
Ghada Kachachi, from United Nations' children's agency Unicef, uses Ms Anyiel's case to explain why funding was stopped for CEAWC's return programme.
She says those who are freed must be helped when they get back home - both economically and socially, as they move from an Arabic society to the Dinka community some left 20 years ago.
But campaigners say the first priority must be to free them from slavery and then sort out the details of their return.
Ms Kachachi also points out that it can be difficult to trace the parents of children abducted in a war zone up to 20 years ago.
Some have forgotten their real names and where they come from, although they can sometimes be identified by the marks cut into their faces as children - a part of Dinka traditions.
Save the Children UK is still helping foster parents look after some children several years after they returned "home".
While officials debate the best way to organise the return, Mr Arol and many others are just desperate to see their loved ones again.
He has gone to meet four different convoys of returned abductees in the hope of being reunited with his family, only to be disappointed each time.
"I always ask God, why other children come back but not mine. What have I done to deserve this?" he asks.
