Life for the Thongchum family can be divided into two very distinct periods - before and after 18 September 2010.  Up to that fateful day, husband and wife Kamol and Manee had lived a simple but happy existence.  With their four young girls Jib, Jiji, Jean and Om, they shared a small but cosy one-bedroom house on a quiet rural road several hours from Bangkok.  Every day when school finished, the two oldest, Jib and Jiji, helped their parents with the family business: selling garlands of flowers to passing motorists on the forecourt of a petrol station.  But events on that Saturday evening cast a long and dark shadow.  At six that evening Manee retreated to the privacy of their pick-up to feed Om.  As the baby was being fed something happened to Jiji.  CCTV footage retrieved from a nearby 7-Eleven store shows the nine-year-old looking for customers, then apparently distracted, moving out of view.  "Initially we thought she'd gone to the rest room so we didn't panic," Manee said. "Then we opened the cubicle doors and saw that she wasn't there."  A quickly arranged search found one of Jiji's flipflops on a footpath near the toilets. But at the local police station her parents' appeals went unheard.  The Thai police are reluctant to take a missing person report until a full 24 hours have passed.  "If they'd started to look quicker I'm sure I could have got my daughter back," said Manee.  Things did not improve once the report had been taken.  Instead of triggering a nationwide search, Kamol and Manee say they were left alone to try and find their daughter.  And for the last three years the Thongchums have done exactly that.  They have driven to 17 of Thailand's provinces. Sleeping in the car to save money and using donations from friends, they've followed up tip-offs and printed leaflets and posters.  It has become a desperate journey. Each fragment of fresh news bringing soaring hope followed by crushing despair.  "We were sent a photo to our Facebook page of a girl selling sweets near Pattaya and I was 80% sure that this was Jiji", Manee said of one of the sightings.  They rushed to the coastal town of Pattaya and sat waiting for the girl at the spot where the picture had been taken. Late that night she did come, but it was clear that she was not Jiji.  "It's very sad," Kamol said haltingly. Manee says it was a moment she will never forget.  "It was very, very disappointing," she sobbed. "When we went we were so hopeful that we would bring her back home with us."  Jiji is listed as a "missing person", but if she is still alive it is possible that she has become one of the tens of thousands of South East Asian children trafficked each year.  If that is the case Pattaya is a likely destination. A sleazy tourist town on the Gulf of Thailand, it has become infamous as a sordid magnet for trafficked children and paedophiles.  Each night Malina Enland, from the faith-based charity XP Missions, walks Pattaya's grubby streets.  As sunburnt tourists ogle lady-boys, prostitutes and sex shows, she tries to locate vulnerable children who need her help.  Legally Ms Enland cannot step in to rescue the children herself, so she calls in social workers and the Thai police.  "It's exploitation of poverty. That's what trafficking is," she said. "Human beings are being brought here to satisfy the demands of men, in particular men from the West."  She says many of Pattaya's street kids are trafficked Cambodians and that they have often been bought for as little as $300.  In one recent case a Cambodian woman sold her two granddaughters to traffickers. Thanks in part to Ms Enland, one of the girls has been found and rescued.  Official statistics, though limited, show almost all the trafficked children found in Thailand have been made to work either as beggars or as child prostitutes.  "In the old days in Pattaya sex workers would be women but now they are girls and boys," Sudjai Nakpain, a social worker, said.  Despite the much publicised efforts of both the Thai police and international law enforcement officers, she says the situation in Pattaya is not improving.  "I can still see it's going on and the authorities never take it seriously. They just see cases involving children as too complicated."  Jiji's parents say they would rather not think about what their now 11-year-old daughter is doing now. Their focus, they say, is simply finding her.  In the absence of help from the Thai authorities they have been grateful for the support of a small charitable organisation called The Mirror Foundation.  It runs what appears to be the only functioning database of missing (not necessarily trafficked) people in Thailand.  Its head Eaklak Loomchomkhae said they received about 500 reports every year. Seventy percent of those result in the person being found.  "The police know how many cars go missing each month, they know what type of car and what has been done with the stolen cars," he said scathingly.  "But for missing children they have no answer. They can't even tell us how many children are missing, how many have been rescued and what has happened to abducted children."  In 2011 the Thai police launched the Missing Persons Management Centre (MPMC). It was supposed to be a focal point for sharing information about missing people in Thailand.  The BBC spoke to Police Colonel Assanee, the head of the MPMC, four times over the course of several days for this story.  He was unable to give us any information on how many missing people were on the database and how many had been found.  For Manee and Kamol the search goes on. After a long absence they have returned to work at the petrol station where Jiji disappeared.  Manee sells fruit and Kamol pastries, but their daughter's absence is never far from their thoughts.  "Everything has completely changed. We used to go everywhere as a family," Manee said.  "The songs that we used to listen to, the food that we used to eat . All those things we used to do together we have stopped."
Hundreds of people in Thailand, including children, are reported missing every year. The BBC's Jonah Fisher looks at one family's desperate search for their daughter.