The former chief constable of South Yorkshire Police thought BBC footage of the force's raid on Sir Cliff Richard's home was "intrusive" when he watched it while on holiday in Wales.
David Crompton, who was head of the force at the time of the search, said he "became very concerned" because the television coverage was "something more" than he expected to see.
In a witness statement to the High Court, he said: "I had thought that there may be some limited footage of my officers going into Sir Cliff Richard's property.
"What I saw was much more extensive and I thought it was intrusive."
The 77-year-old entertainer is claiming "substantial" damages for what he says was a "very serious invasion" of his privacy when the raid on his home was broadcast in 2014.
The coverage included footage taken from a helicopter flown above the singer's home on a private estate in Sunningdale, Berkshire.
The BBC contends there was a "legitimate public interest" in its coverage and is vigorously defending the case.
Mr Crompton said he first became aware South Yorkshire Police would be investigating Sir Cliff in the summer of 2014 and was later told BBC reporter Dan Johnson was aware of the investigation.
He said: "I can remember very clearly thinking that there was a journalist who knew as much as I did about the allegations.
"This information was deeply concerning to me because I thought that a media report on a high profile case, which was in its infancy, could fatally compromise SYP's ability to carry out a thorough investigation which, as I have said, was my priority.
"The thought of a journalist reporting on the investigation before SYP had been able to conduct the search was a particular concern."
He said he believed the story was "bound to come out" now the media were aware and he thought the BBC were likely to report it "imminently".
He added that providing the BBC with information about the search was a "small concession" which he decided was necessary to "protect the integrity" of the investigation.
Sir Cliff was accused of molesting a teenager at Sheffield United's Bramall Lane during a rally led by the Evangelical preacher Billy Graham in the 1980s.
But no charges were brought against the singer after an investigation lasting almost two years.
South Yorkshire Police has already paid £400,000 in damages to the singer.
The hearing is expected to conclude next week.