Michael Silverleaf, counsel for the Home Office, said Mike Morley, a producer with Central Television, was recorded in the Albany prison gate book as a psychologist when he made a preliminary visit to see Nilsen with Paul Britton, a clinical psychologist for the police and also a consultant to Central.
When Mr Morley returned the next day with Mr Britton and two police officers involved in the research, he did not identify himself as a Central producer. Later, the film shot by Mr Morley was taken by police because the Home Office had refused permission for Nilsen to be filmed.
Later, Mr Britton took his film to Central for copying, although it was still only for police purposes. 'Unknown to him, Mr Morley had surreptitiously arranged for a further recorder to be attached to the machine,' Mr Silverleaf said.
The Home Office was asking Mr Justice Aldous for an injunction banning Central from showing a four-minute extract of the four hours of recorded interview between Nilsen and Mr Britton, due to be included in the documentary Murder in Mind, scheduled for screening on Tuesday.
The Home Office says that as Mr Britton organised the interview and was engaged on Home Office research, the copyright resides with it. The film also breached the policy that serious offenders were not allowed a public platform. Nilsen was jailed for life in 1983 for the murder of six men; he claimed to have killed a further 10.
In an affidavit read to the court, Mr Morley said that although he was shocked when police told him permission was being withheld, he did not raise the issue because he was concerned Nilsen would withdraw co-operation. The agreement from Nilsen was that no police were present and it would be broadcast; Nilsen was not told the two other men present were police.
Mr Morley denied making a false entry in the gate book and said he had correctly identified himself to the prison deputy governor. 'Nothing was concealed. If they did not know who I was, then I am amazed I could have been allowed in a high security prison with television equipment.'
At the end of the hearing, the court went into private session to view the film. The hearing resumes on Monday.