The man at the centre of a gang which is alleged to have driven a man with a mental age of six to his death was a nasty piece of work, Truro crown court has heard.

The jury in the trial has heard from a number of young witnesses, some of them vulnerable, about life in the flat in Blowinghouse Close, St Austell with alleged gang leader Darren Stewart and Steven Hoskin the man he is said to have killed.

One former girlfriend said that Mr Hoskin had been a "good bloke" who had been taken advantage of by other people. Things had changed when Darren Stewart began living in the flat and "basically took over".

Stewart, who used to take "speed" almost every day, had said that Mr Hoskin was a pervert "but I never saw any sign of it." She had seen him be aggressive and violent towards Mr Hoskin, who would not fight back. He would get upset and start crying.

"Steve thought they were friends but Darren wanted the flat for himself," she said.

The teenager told of Stewart often saying he was going to commit suicide before the jury heard taped conversations with the police in which Stewart pretended to be Mr Hoskin reporting that he (Stewart) was missing and had taken his razor blades and tablets with him.

She also claimed that Stewart had forced her to take three "Speed bombs" and four tablets as a result of which she was taken by ambulance to Treliske Hospital.

During cross-examination the girl said that after Stewart moved into the flat more alcohol was consumed and Mr Hoskin became drunk almost every day.

"I liked Darren at the beginning and was in love with him until he became nasty. But I was too scared to leave him." While she was his girlfriend he was also seeing two other teenagers. It was quite common for him to play one off against another.

Another former girlfriend said that Stewart had threatened suicide and to kill her. He had hit her in the stomach and she had had to go to hospital because of the pain.

She also said she had warned the female defendant against him but had been ignored. "There were a number of women after him," she declared. "Other youngsters seemed to idolise him and think he was a 'big man'."

A neighbour told of seeing Stewart hit Mr Hoskin in the face and him cowering in the corner of the settee. He had been present when Mr Hoskin had referred to child molestation, saying "The only thing I have been done for was messing around with kids".

Another witness said that Stewart had treated Mr Hoskin "like a doormat" and could walk all over him and do what he wanted, and another that when on "Speed" Stewart could be a ' really really nasty bloke'. He had seen Stewart push Mr Hoskin against a wall and punch him in the stomach A youth who was aged 15 at the time of the incident told the jury that during the evening of July 5 last year Stewart had provoked an argument with Mr Hoskin and pushed him around. The girl told Stewart to fetch a dog choker lead and put it around Mr Hoskin's neck and he was made to move around on all fours in the kitchen. He was also told to get beers for people and to bow to them.

Mr Hoskin was made to sit with his hands on his head and he had to ask for permission to flick ash from his cigarette into an ashtray.

The witness said he decided to leave after the girl asked Stewart to make Mr Hoskin tell everybody what he used to do. Mr Hoskin told the group - there were eight people present - that when he was about 20 he used to touch a young boy's private parts.

The final witness on Tuesday was a youth now aged 15 who recalled that it was the girl who put the dog chain around Mr Hoskin's neck. He was so disgusted at what was happening in the flat that he also decided to leave.

Mr Hoskin died after he fell 100 feet from a railway viaduct in St Austell.

Stewart, 30, Martin Pollard, 21 and a girl aged 17 who cannot be named deny murdering Mr Hoskin. Two boys, aged 16 and 17, from St Austell deny assault occasioning actual bodily harm.

The trial continues