Berlin Letter: Heidi Stein has lived every mother's worst nightmare for the last 28 years, when her three-year-old son Dirk vanished without trace on holidays. But her tragedy took an even more menacing turn when her desperate campaign to find her child attracted the attention of the East German (GDR) secret police, the Stasi.
After nearly 30 years, Ms Stein remains convinced that the secret police were involved in her son's disappearance.
"I just hope that perhaps there are people out there who are today more willing to say what happened," said Ms Stein, a blonde woman with a tired, friendly face.
In Mary 1979 she and her then husband headed off on holiday with their two children Silvia, then seven, and Dirk to the Harz, a popular holiday destination with beautiful mountains and forests.
One day they visited a mountain cave and, to relieve the boredom of queuing, Heidi let the children play beside the nearby car park.
That was the last time she saw Dirk: Silvia came up to her a few minutes later but didn't realise Dirk had vanished. An immediate search began but no body was ever found.
In desperation Ms Stein wrote letters to GDR leader Erich Honecker and also to Amnesty International and the Red Cross.
"We thought at the time that by writing to western organisations, pressure would come on the GDR from above and that Honecker would do something," she said. "Honecker did something all right, he made sure I went to prison." Six months after Dirk disappeared, the Stasi began pressuring Heidi and her husband to sign a document declaring him dead.
The couple refused and applied for permission to leave the GDR. Their application was refused and Ms Stein found her campaign increasingly frustrated by the authorities.
Police had never officially declared Dirk missing, nor did they follow up her lead about a couple driving away suddenly from the car park when Dirk vanished.
Finally, the entire police file of the investigation vanished without trace.
Ms Stein's legal battle with the authorities ended in 1983 when she was sentenced to four years in prison for contact with western organisations.
"That's when I finally realised that there was something abnormal about our case," she said. "You didn't go to prison for looking for a child." After 18 months behind bars, she learned that she was one of the prisoners Bonn authorities regularly "bought" free from the GDR.
After the fall of the Berlin Wall in 1989, she hoped to turn up new information in the archive of the now defunct Stasi. Although her case was well-documented at the time, the archive was now empty, suggesting the paper trail was removed.
Ms Stein is convinced that Dirk is still alive - he would be 32 now - and that he is perhaps living in Russia.
"For me he is not dead," said Ms Stein. "If he was dead, if he had drowned or something, we would have found his body. If he was dead, I think the Stasi would have wanted me to know."
