The Crown prosecutor called 22 witnesses which included former hitchhikers and associates of Von Einem. The police had really done their homework and had left no stone unturned in their efforts to nail what they believed was the most heinous killer in Australian history.
The first prosecution witness would only give testimony under an alias of "Mr. B" for his own protection and his name was withheld from publication by court order. Mr. B claimed that he believed that Von Einem had killed 10 young people, including five children who had disappeared 24 years earlier.
Mr. B denied that he was a "perpetual liar," and that a reward over the unsolved murders of several Adelaide teenagers, which stood at $250,000, had anything to do with his giving information to police.
In an angry outburst, Mr. B claimed that consideration for relatives of the deceased was part of the reason he was telling what he knew of Von Einem's activities. "I have given a lot of consideration to the relatives of the kids. They deserve to know what's really happened," he told the court.
Mr. B was a former friend of Von Einem's and a homosexual. He said he had evidence that linked Von Einem with the five Family murders and also the disappearances of the three Beaumont children in 1966 and the 1973 disappearance of schoolgirls Joanne Ratcliffe and Kirsty Gordon from Adelaide Oval. The courtroom was stunned. They couldn't believe what they were hearing.
For four days Mr. B testified how he and Von Einem picked up young boys who were hitchhiking and drugged them and raped them. On the night that Alan Barnes had died he and Von Einem went looking for hitchhikers after meeting on the banks of the Torrens River.
He said that they gave Alan Barnes a lift and gave him alcoholic drinks containing a very strong sedative called Rohypnol which they knew that when mixed with alcohol would induce unconsciousness. They all then went into a café where Barnes was obviously affected by the drug and was showing signs of passing out.
Von Einem went away and made a phone call and when he came back said that he had rung a friend and had arranged to meet him back at the Torrens River. They met up with a man known only as "Mr. R." Von Einem went for a walk with Mr. R and came back ten minutes later and asked if Mr. B would like to go with them while they "performed some surgery" on the now unconscious Barnes.
Von Einem went on to say that they also intended to take videos of what happened, then kill Barnes and throw his body from a bridge. Mr. B told the hushed courtroom that he had declined the offer and Von Einem, Mr. R and the unconscious Barnes had driven off.
Mr. B said that he saw Von Einem a few days later and he said that the youth had died and that Mr. R was concerned about what Mr. B knew about what happened. Von Einem then warned him that if he said anything to anyone about what he had seen then he would be implicated in the murder as well.
Mr. B then explained that since that night his life had been a mess and he lived under the constant threats of an "Adelaide businessman."