CHRISTOPHER Halliwell tried to portray himself as a normal family man and claiming he was "quiet and reserved", but behind the caring image lay a sinister past.

To the outside world he was a responsible father-of-three and hard-working taxi driver, running his own business yet behind closed doors the 52-year-old hid the fact he had killed two women and dumped their bodies.

Although some may have been shocked that the popular cabbie was a murderer, it came as no surprise to Halliwell's sister.

Sarah Halliwell said her brother had a dark side and displayed a "disturbing" aura.

"He was just not a normal child. I have witnessed things he did at first hand, and it was very unpleasant," she said in an interview in 2011.

"He loved trapping spiders and butterflies and taking his time to pull off their legs and wings one by one.

"It was like a hobby to him and he showed no emotion while he was doing it. He has always lived in a strange world of his own."

Miss Halliwell, who had not spoken to her brother for more than two years,  said he had chilling blue eyes.

"He is a very cold, detached person who could never handle normal relationships," she said.

"If you ever had a go at him he would just stare you out with those vile eyes and say nothing."

Halliwell managed to keep his dark past hidden from those closest to him and he probably thought he had got away with his first murder, as no one was actively looking for drug addict Becky Godden.

Halliwell carried on his life as normal running his own chauffeur taxi business and living with his wife in a semi-detached house in Ashbury Avenue, Swindon.

He had met Lisa when she was 16 and he was 23. They married in the mid-1990s and had three children together.

He had starting paying Swindon prostitutes for sex after his wife had their third child in 1996.

"After Lisa had Shane in 1996 she went completely off sex, I didn't,"

Halliwell told police.

"I'm not going to say I was out there every single night trying to get it. I didn't want an affair, I didn't want a relationship.

"Occasionally, I would use a call girl. They work in a certain area around Swindon. There's no emotional involvement.

"Obviously, with an affair there's a danger you get too emotionally involved and it would ruin your marriage.

"It was a sensible escape rather than getting into an affair."

They split in 2005 when Halliwell moved in with neighbour Heather Widdowson.

Halliwell had drifted from job to job, including spells working as a window cleaner and in the building and construction trade.

He became a taxi driver and then ran his own chauffeur business but in January 2010 he was declared bankrupt and returned to private hire cabs.

Halliwell had only been working for Five Star private hire for a couple of weeks when he struck again, murdering Sian O'Callaghan.

One taxi driver, who used to work with Halliwell, said at the time: "He works the late shifts and is a regular on the nightclub runs.

"He's slim and has piercing blue eyes and I suppose women would find him quite attractive."

In the knowledge that he had killed the office worker, he attempted to keep up a cool facade by putting a poster offering a £20,000 reward appealing for information on her whereabouts in the rear window of his taxi.

Within three days of her disappearance, Halliwell was the police's main suspect with detectives believing she had got into his green Toyota Avensis.

The taxi driver was placed under 24-hour surveillance and when he was seen buying enough paracetamol for an overdose, he was arrested.

Halliwell spoke to Detective Superintendent Steve Fulcher on the day of his arrest and confessed to murdering the two women and showing the officer where he had left their bodies.

He admitted he was a "sick f*****" and "normal people don't go round killing each other".

There was almost a second attack of consciousness last year when he was interviewed by police on suspicion of Miss Godden's murder.

As he faces life behind bars, he will be able to contemplate a third.