"He looked lively and was taking short paces. I said: 'I wouldn't know, I'm not a murderer'.
"He was coming up with ideas about whether he should set her on fire with petrol in his bedroom or drown her.
"My reaction was to think: 'Christ, you're nuts. That's insane'.
"He also mentioned a drugs overdose or whether she would choke on her own vomit if she got really drunk."
The two friends then started play-wrestling and Mr Crowe tried to show him how wrestlers strangle each other on television.
"He is very muscular, powerful and strong because he drinks protein shakes and goes to the gym.
"He took hold of me the same way and put a lot of pressure on my throat and I started to panic.
"I was struggling and said: 'Can you get off'. I held my breath and tapped him on the arm to let go."
Mr Crowe earlier told the court how on April 30 last year, Turner claimed he killed Ms Longley with a hammer.
He said: "Elliot said he found out Emily was going to a nightclub on a date with another boy by looking through her Facebook and phone messages.
"We drove there and on the way he was very angry and aggressive, banging the steering wheel and speeding.
"He had a hammer and said he was going to batter her and the boy to death with it.
"He put the hammer in his trousers and went in the club while I waited in his car.
"After three hours he came out and he was in tears and said he had done something awful.
"He said he had hit her six or seven times with the hammer and killed her.
"He was very convincing, I was in shock. He said he was going to hand himself in to police.
"We then picked up our friend and he told him the same story.
"But then he said 'only joking' and he stopped crying and was cheerful, jumping up and down.
"I was really annoyed with him because I thought he had actually killed her and had led me on."
Mr Crowe told the court he feared his close friend Turner was going to murder Emily during the hours before she died.
That night he confided in Turner's neighbour Harry Hawkins, 18, saying "I think Elliot might kill Emily."
Mr Crowe also revealed Turner had asked him to kill Emily with the hammer, but he had refused.
The three drove back to Turner's home at about 12.50am on May 7.
He said: "Elliot and Emily went inside while I waited outside.
"After about 15 minutes Elliot rushed out with Emily's mobile phone and was going through her text messages.
"There were messages from Louis Powell and Elliot was swearing lots.
"We then went inside and Emily was lying on the bed and Elliot discreetly put the phone back.
"They seemed happy and Elliot asked me to leave so I phoned for a taxi, said my goodbyes and waited outside.
"Then Elliot came out in a T-shirt and boxer shorts to smoke a cigarette.
"He approached me and asked me to kill Emily. He said 'I want you to kill her.'
"He picked up the hammer and pushed it into my chest.
"I was shocked and told him I'm not doing it, no chance.
"Then Emily stuck her head out the door and shouted at Elliot 'I hate you' and tried to lock him out.
"She was telling him to f*** off.
"Elliot pushed his way back in and that was the last I saw of him. After a few minutes the bedroom lights went out.
"In the minutes before, Harry Hawkins, Elliot's neighbour came out and I said to him 'I think Elliot is going to kill Emily.'
"I was scared for Emily and shocked but didn't know what to do. I didn't think he had the balls to do it.
"My taxi came and I got in, I was relieved to get away."
Emily, a student from Auckland, was found dead in Turner's bed at the house in Bournemouth, Dorset, on May 7 last year.
Winchester Crown Court heard Turner "flipped out" and killed her during a drunken argument.
Jurors were told he had become increasingly suspicious she had been having affairs during their four month relationship.
Emily changed her Facebook profile picture from one of them together during a three-week holiday to New Zealand in April.
Turner then allegedly left a message on a friend's voicemail saying: "She changed it to her flirting with some other lads and made me look like a nob."
The court heard Turner later threatened to kill the blonde teenager with a lump hammer and boasted to her "I will go to prison for it and still be a millionaire when I come out."
Turner allegedly even demonstrated on Mr Crowe how to strangle someone and applied so much pressure his friend could not breathe.
After the murder Turner is said to have written a letter of confession but it was ruined with bleach by his father, Leigh Turner, 54 to "destroy vital evidence."
Turner was arrested following Emily's death but then released on bail.
Jurors heard a police bug of the £350,000 Turner home in the affluent Queens Park area recorded the family talking about "fabricating evidence and being worried about lying to police".
The court was told that after the death, Turner's mother, Anita, 51, removed from the house a coat her son had worn on the night of aspiring model Emily's death.
Police scans of computers seized from the home found Google searches for 'death by strangulation' and 'how to get out of being charged for murder'.
Officers made a series of recordings at the Turners' home between May 18 and June 14 last year.
They then arrested the three family members and charged them in July.
The court heard pathologists who examined Emily's body found injuries consistent with asphyxiation, Turner had scratches on his arm and Emily had his DNA under her fingertips.
Emily was born in Britain but her family emigrated to New Zealand when she was nine and she was raised in Auckland.
She had returned to live with her grandparents in Bournemouth, to study for a business national diploma at Brockenhurst College, Hants, and worked part-time at Top Shop in Bournemouth.
She was also signed up to a modelling agency and had appeared on the front page of a magazine in New Zealand.
Turner denies murder and perverting the course of justice. His parents both deny perverting the course of justice.
The trial continues tomorrow.
- additional reporting: APNZ
