VANCOUVER -- A former RCMP employee says she will never forget the sound of the door being locked behind her by a now-retired inspector who is alleged to have sexually assaulted her in a washroom at their Vancouver workplace.

"I remember the sound just felt shocking, the sound of the lock when he turned it," the woman testified Tuesday as she stared into the distance and turned her hand as if to lock a door.

Tim Shields, who was the public face of the RCMP in British Columbia as the department's spokesman, has pleaded not guilty to one count of sexual assault.

The woman, whose identity is protected by a publication ban, told provincial court she was confused when Shields said he had something to tell her and led her into a unisex washroom at the Mounties' former headquarters in Vancouver in the fall of 2009.

CAUTION: SEXUALLY GRAPHIC CONTENT FOLLOWS

"I remember him saying, 'I found this place and it has a lock on the door,' " she said. "I was really frozen and confused. I didn't know what was going on.

"He went under my blouse. He undid my bra. He touched my breasts. Then he went toward my waist. He unbuttoned my pants and he was trying to unzip my pants when I pushed his hands away and said, 'No, let's go.'"

The woman said when she asked Shields to stop, he stepped back, put her hand on his exposed erect penis and asked her to perform oral sex.

"I said, 'No,'" she testified, speaking slowly and pausing frequently, with her eyes closed. "I just had this sort of, 'Oh, my God,' feeling. I'm not going to be able to get out without something happening."

Shields then did up his pants and washed his hands and face in the sink, the woman said.

"I was against the wall. I was standing quite shocked and he said, 'Don't forget to do up your bra.'"

The woman said she did not feel she could leave the washroom because Shields was standing between her and the door.

"I just remember being quite scared about the whole thing and wanting to get out," she said.

The woman also told the court she rebuffed earlier advances from Shields, saying she felt uncomfortable and embarrassed in July 2009 when he told her in a parking lot outside work that he found her sexually attractive.

Later that summer, he told her he would like to perform oral sex on her, she said.

After she declined, Shields asked her not to tell anyone because it would be "bad for him," the woman said.

"He asked if he could trust me," she said. "I believe I said, 'Yes.' "

Shields left the RCMP in December 2015 and was charged the following May.

The woman told court last week she was diagnosed with post-traumatic stress disorder after leaving her civilian job with the RCMP.