A San Francisco police officer has been accused of rape by a woman he met while on patrol, and police officials are investigating whether a lieutenant lied and delayed the investigation, court records show.

According to an affidavit for a search warrant, obtained Tuesday, the officer frequented the alleged victim’s workplace while on patrol from the Taraval Station, and asked her to dinner on Aug. 2.

When he arrived at her Sunset District home that night, the two began drinking heavily in the kitchen, with the alleged victim stating she had five to seven hard liquor drinks in the first half hour, wrote police Sgt. Joseph Minner in the affidavit.

When the woman’s roommate and the roommate’s mother arrived, Minner wrote, the officer suggested going to the bedroom. The alleged victim said that when he tried to pull her pants down, she said, “No, I don’t want to.”

According to the affidavit, she said she kept saying no, and when the officer asked if she had a condom, she said no again, in hopes of dissuading him.

The officer had sex with her anyway, she said, holding her arms down as she tried to fight him off. She “fell asleep,” the search warrant states, and when she woke the next morning, the officer was raping her again.

The woman said the officer ejaculated on her bedsheets and comforter cover. The search warrant asked for a sample of his DNA.

The officer told the acting station captain that he “got hammered and does not remember anything else,” the affidavit states.

Officer Albie Esparza, a Police Department spokesman, said the agency is working with the San Francisco District Attorney’s Office to “conduct a thorough, complete investigation.”

“Once the alleged sexual assault was reported, the officer was immediately placed into a non-public contact assignment and relieved of his department issued firearm,” Esparza said.

The Chronicle is not naming the officer because he has not been criminally charged.

The search warrant affidavit also says that police Lt. Curtis Liu contacted the officer to tell him that he was named as a suspect in a rape on Aug. 7, the day the woman sought medical treatment at San Francisco General Hospital.

Liu then repeatedly lied to his superior officers about contacting the officer, Minner wrote, and led them to believe he had made proper notifications to start an investigation.

The lies and breach in protocol, Minner wrote, not only delayed the investigation by a day but “could have assisted (the officer) in destroying and disposing of crucial evidence in this investigation.”

“It is my belief that Liu intentionally interfered with a felony sexual assault investigation both by lying to the officers investigating the incident and by contacting the suspect, directly to inform him of the investigation and the progress of the investigation,” Minner wrote.

Hospital officials alerted police when the alleged victim arrived at the rape trauma center on Aug. 7, but she initially declined to speak to the officers who responded, Minner said. However, she provided a name and description of the suspect, as well as the location of the alleged assault. She later gave a full account to police.

The investigation into Liu’s role reportedly began when the officer called an acting captain, Cornelius Johnson, to say Liu had told him he was a suspect in a rape.

According to the search warrant, when Johnson asked Liu if he had spoken to the officer about the sexual assault, Liu said he had not. Liu said he notified Una Bailey, the acting captain of Taraval Station, who then made the proper notification to her superiors.

Liu was asked several times again if he had contacted the officer, and each time he denied it, the search warrant reads. But the officer said he had received a copy of the incident report from Liu, and that Liu had asked him several questions about whether he knew the victim, where he met her and if they had sex, Minner wrote.

When investigators later told Liu they knew he had contacted the officer and asked him if he had lied, he reportedly responded, “Yes.” According to the search warrant, he contacted the officer because he was his friend.

Minner wrote that Liu explained that he had actually called the officer as a joke, not believing he was the person accused by the woman. The officer’s name is relatively common.

Tony Brass, Liu’s attorney, said the call was unintentional.

“He thought that the name was nothing more than a coincidence,” he said.

Brass said Liu had alerted internal affairs about his mistake, but did not get a response.

“Liu has had a spotless career with the San Francisco Police Department,” Brass said. “He has been a very good cop for many, many years and right now he is dealing with a mistake in procedure.”

Staff Writers Jaxon van Derbeken and Evan Sernoffsky contributed to the reporting of this story.

Vivian Ho is a San Francisco Chronicle staff writer. E-mail: vho@sfchronicle.com Twitter: @VivianHo