The box weighed about 132 pounds and so it was not possible for one person to transport it to the location in the forest. However, speculation and tips led the police to one man, Werner Mazurek, who was a television repairman and lived close to the Hermanns. Werner owed a bank 140,000 DM, so the police assumed he had a motive.
When the police questioned him he took a day to give an alibi that he was playing Risk with his friends and wife. Police made a search of his house but failed to find any evidence of his involvement in the crime. About four weeks later police questioned Pfaffinger, an acquaintance of Mazurek. Pfaffinger revealed that he had dug the hole and seen a box placed inside at a later date.
However, when asked to lead the interrogators to the spot in the forest he could not find the location. Later he withdrew his confession and refused to repeat it over several interrogations. He was released without charge.
By mid-1982, the lead detective connected with the case was replaced. The investigation was made wider. More evidence was found by the new police team of the kidnapper using an alert system based on a wire strung on the trees. However, their investigating came to nothing. The investigation slowed down by the late 1980s.
Then, in the mid-2000s, the criminal investigation team began looking once again into previous cold cases, and it took up the Ursula case. Evidence gathered previously was re-examined painstakingly. DNA profiling which was not available earlier was now used on hair samples that were found. Several people were questioned but the investigation resulted in dead ends.
As time was running out to bring a conclusion to the case, the prosecution stepped up its efforts. Pfaffinger had passed away but Mazurek was still living. In 2007, Mazurek was placed under surveillance, and later in October of the same year, a sample of his saliva was taken to compare with the DNA on one found on a screw of the box. There was no match.
The prosecutors turned their attention to a tape recorder that was in the possession of Mazurek during an earlier search. An expert on sound did tests that verified that it was used in the kidnapping for playing the jingles. Mazurek and his wife were arrested in October 2008. He claimed innocence. The trial went on for 55 days, and on 25th March 2010, he was sentenced to life imprisonment and his wife acquitted.