An oddball loner who was sacked from McDonald's went back to the restaurant and hacked a colleague to death.

Shane Freer, 21, who had severe Asperger's which had not been diagnosed, bought an eight-inch hunting knife after being dismissed for punching a customer in the face.

He took the weapon back to the fast food restaurant and launched a "horrific, frenzied, ferocious and crazed attack on a defenceless woman".

Grandmother Jackie Marshall, 57, had worked at the branch in Terminus Road, Chichester, for 15 years. She was stabbed six times and died from a three-inch cut to the abdomen.

Freer was jailed for life yesterday at Lewes Crown Court after admitting manslaughter on the grounds of diminished responsibility.

The jury was told Freer was in a "profoundly abnormal" state of mind before the attack in April last year.

Mrs Marshall, a mother of two and grandmother of three, from Southbourne, near Chichester, died soon after the attack.

Freer, who lived with his parents in First Avenue, Batchmere, near Chichester, blamed Mrs Marshall for his sacking. He told police afterwards: "I had to kill her. She got me fired. She had to die."

Freer, described by colleagues as quiet, shy and reserved, had worked at the restaurant for two years.

Managers said he was not a good communicator and not good with customers but carried out his job to the best of his ability.

McDonald's first became aware of problems on April 9 when he punched a teenager he said was causing trouble in the restaurant.

He told managers he had "just lost it" and punched the girl on the chin because she was blowing pieces of carrot at him through a straw.

Bosses suspended him on full pay and asked him to come back on Saturday April 16 at 11am for a disciplinary hearing. When told at the meeting he had been sacked Freer broke down in tears before mumbling: "I'll kill her."

Simon Russell-Flint QC, prosecuting, said: "At some point he said he was never told he could not hit people.

"Then he said there was nothing else left but to kill her. He said: I'll get a knife and stab her'.

"It was assumed he was referring to the female customer he had struck."

Freer left the restaurant at 11.50am, went straight to a nearby ironmongers and bought an eight-inch knife for £32.95.

CCTV pictures showed him returning to McDonald's just after 1pm with a rucksack.

Mr Russell-Flint said: "By now he appeared to be very angry and agitated and seemed as if he was talking to himself.

"There were 30 to 40 customers in the restaurant and many of them were teenagers or children."

At 1.16pm Mrs Marshall was standing near a cleaning cupboard when Freer walked in, was seen to take the rucksack off his shoulder and walked htrough the restaurant "with clear intent and purpose" towards her.

Mr Russell-Flint said: "She was heard saying no, no, no'. The defendant was seen to hold her with his right arm and he appeared to be punching her.

"She screamed and he appeared to hit her a number of times with full-blooded punches to the face.

"In fact he was stabbing her repeatedly with the knife and she collapsed onto the floor."

Freer was grabbed by a number of bystanders including an off-duty Metropolitan Police officer.

Other customers began to scream and panic and fled towards the doors.

Mr Russell-Flint said: "When he was grabbed the anger and rage disappeared from his face and he seemed calm and normal."

Freer shouted: "I can't cope any more."

He told the officer: "She lost me my job and I'm going to kill her. She had to die."

Before she fell unconscious Mrs Marshall was heard to say: "Please help me, I'm dying."

Mr Russell-Flint said: "He attributed blame to Mrs Marshall which was perplexing.

"This was a cold-blooded and merciless killing motivated by anger and revenge."

When he was suspended he had asked Mrs Marshall to act as his witness.

Freer was arrested and charged and remanded in custody in prison before being transferred to Broadmoor hospital in April this year.

Mrs Russell-Flint said: "He told psychiatrists that having been dismissed he felt he wanted to kill Mrs Marshall and his feelings were getting stronger and stronger.

"He could not get the thought of killing her out of his mind. He felt he had no option and that she had destroyed his life.

"He thought it was fair that he had killed her."

The court heard Freer had previously punched a teacher and once took a knife to school with the intention of slashing the throat of a girl who had been taunting him.

Five psychiatrists agreed that he was a "grave and immediate danger to the public if at large."

Mrs Russell-Flint said: "He does not regret the incident and says he would do the same thing again in similar circumstances.

"He has no understanding of the impact of his actions on his victim's family."

Anthony Donne QC, defending, said: "This offence was committed by a very disturbed young man. He suffers from a very pronounced degree of autism.

"It is a very complicated condition. He lives completely in his own world with no ability to relate or respond to situations of every day life that most of us cope with on a daily basis."

He said Freer's parents were in no way to blame for the condition not being diagnosed before.

Mr Donne added: "This young man is very dangerous because of his condition."

Judge Anthony Scott-Gall gave Freer a life sentence and ordered him to serve a minimum of four years.

But he ordered him to be detained indefinitely at Broadmoor maximum security hospital.

He added: "I am required under law to pass a custodial sentence but that sentence is entirely academic.

"This was an dreadful killing committed in cold blood in full view of members of the public out for a family lunch.

"One cannot begin to contemplate the impact on the family."

Freer, who sat in the dock flanked by five guards, showed no emotion as he was sent down or while the details of the case were outlined to the court.

There was no sound from a public gallery packed with Mrs Marshall's friends and relatives.

Her husband Eddie, 67, to whom she was married for 38 years, said afterwards: "It's going to take some time to get to grips with this.

"There are a lot of unanswered questions and our family has to do a lot of talking. In the meantime we would appeal for privacy."

Mrs Marshall's manager at the restaurant, Neil Jones, said she was the best employee he had ever had.

He said in a statement: "I do not remember a time when she was not smiling."

Colleagues described her as a mother figure who worked tirelessly for charity.

Staff and customers were devastated after the killing and were offered counselling by McDonald's.

Senior investigating officer detective chief inspector Russ Bagley, of Sussex Police, said: "This was a particularly savage attack on a lovable lady who was popular with everyone.

"Our thoughts are with Eddie, Jackie's husband, and the rest of the family, who have been devastated by their loss."

Chief inspector Mark Eyre, Chichester district commander, added: "This was a very sad event, which at the time had quite an impact on the community in Chichester.

"Fortunately offences of this nature remain very rare in Chichester and in Sussex as a whole. I would want to reassure people that the police and partner agencies, take tackling the issues surrounding offences of violence in our community very seriously.

"We have been working at an number of levels and have made significant improvements. Chichester is and remains a safe place to live, work and visit.

"Knives are available in all our homes and can be lawfully purchased by people over sixteen years of age. On this occasion the weapon used in this attack was legitimately purchased."