A man accused of murdering a student told police he "felt sorry for her" and offered her a lift when he saw her crying in the street, a court heard.
Pawel Relowicz, 26, was initially arrested on suspicion of abducting Libby Squire, 21, in February 2019.
Sheffield Crown Court heard he denied this during police interview and said he wanted to assist the search effort.
He said he had no idea whether Ms Squire was alive when asked by detectives, jurors heard.
Prosecutor Richard Woolfall told the court the defendant's abduction arrest was on 6 February 2019 - five days after she went missing after a night out in the city.
Reading from a transcript of police interviews, Mr Woolfall said the accused was shown a picture of Ms Squire and asked if she was alive.
"How am I supposed to know?" he asked officers, and insisted he did not abduct her.
Mr Relowicz told officers he had driven to the student area of the city for a run when a crying Ms Squire asked him to stop, the court heard.
He said she was "behaving strangely", as if she had "taken something or someone had put something in her drink".
"I felt sorry for the girl because she was crying," he said.
'Wanted to vomit'
He said Ms Squire gave him her hand and they walked to his car so he could give her a lift home, the court heard.
"I fastened the seatbelt and I could see because the car was warm she felt better," he said.
Police were told Ms Squire was making gestures as "if she wanted to vomit" while she directed him, so he stopped near the Oak Road playing fields, the court heard.
Mr Relowicz then told officers Ms Squire got out of his car - falling over as she did so - and "kept kneeling there and crying" in the snow.
He said he got back inside the car and could see Ms Squire walking on the pavement on as he drove away.
"I've not seen her since. I didn't know if this was her home address or not," he told police.
As the interview went on he described going home to bathe and watch a film before returning "at some point" to see if Ms Squire was "lying anywhere", the court heard.
He said: "I drove but there was nothing lying so I drove round and that was it."
Earlier on Tuesday, the jury was shown CCTV video of movements from both Mr Relowicz and Ms Squire from when she was last seen on Beverley Road on 31 January 2019, after the student was refused entry from The Welly nightclub.
The footage showed the defendant walking with Ms Squire, from High Wycombe, before driving to the Oak Road playing fields.
He then leaves by himself and travels around the student area of the city, before performing a sex act upon himself on a main road and returning home shortly after 03:00 on 1 February.
The trial continues.