A Thanet acting detective sergeant advised a woman who claimed she had been repeatedly raped to phone the Citizens Advice Bureau, a jury has heard.
She had made her detailed allegations to a police constable and was then taken to see Mark Thorne at Margate police station.
But the man she said had attacked her was not arrested - until he was alleged to have carried out one more attack.
Mark Thorne was an acting detective sergeant at Kent Police
The Acting DS - who is under investigation by Kent Police - told a jury at Canterbury Crown Court he was not aware of her claims.
Thorne told the jury: "When I discovered her allegations I was sick to the stomach, because I thought who is going to believe that I never knew about that."
Alan Lucas, of Bromstone Road, Broadstairs, had denied the rape charges and was acquitted by a jury after six hours of deliberations today.
The 48-year-old's barrister Simon Taylor called Mr Thorne - who is now a detective constable - to give evidence for the defence after he interviewed the alleged rape victim in May 2012.
"She wouldn't disclose anything. I tried to empathise to help her to open up. There was clearly something she was unhappy about..." - DC Mark Thorne
He said he had received a call from a uniformed officer who had interviewed her.
Mr Taylor asked: "As a consequence of your involvement with (this case) are you now being investigated by the Professional Standards Department of Kent Police?"
The officer, who has been with the Kent force for 22 years, replied: "Yes".
He said he asked the woman four questions regarding the allegations and then gave her advice, which included showing her a leaflet from the Citizens Advice Bureau.
"I understand what the law says about rape so I explained to (her) that she would have had to object to sexual intercourse.
"I told her that the police had to deal with criminal law, although we can offer some guidance and advice and then I went through appropriate ways in which she could do it, Citizens Advice. I went through the leaflets. I told her there were contact numbers that might be useful.
"But she wouldn't disclose anything. I tried to empathise to help her to open up. There was clearly something she was unhappy about.
"So I arranged for her to be taken home again. I have had no dealings with her since that date."
The case is being heard at Canterbury Crown Court
But the detective claimed he was not told that she had already made detailed accusations - outlining detailed claims of rape.
He admitted he had not created a crime report, despite the earlier allegations.
Prosecutor Christopher May told the jury the woman had phoned the police and had made an allegation of rape - and a PC was sent to interview her.
He said the woman had made a detailed complaint of being raped and she was then taken to Margate police station.
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