A husband who helped his wife to kill herself rather than watch her continue to suffer from a debilitating disease was given a 12-month suspended sentence yesterday.

Robert Cook, 60, admitted manslaughter on the ground of diminished responsibility and aiding and abetting his wife’s suicide. As he left the dock at Lewes Crown Court, he bowed to the judge and said: “Thank you.”

In the latest of a series of so-called “mercy killings”, the court was told that Cook suffocated Vanessa, his wife of 29 years, with a plastic bag after she took an overdose in their Sussex home in October 2006.

After she died, Cook called the emergency services. As they tried to resuscitate his wife, he told them: “She wouldn’t thank you for your efforts.”

Mrs Cook, 55, had a history of depression and previous suicide attempts and in 2003 she was diagnosed with multiple sclerosis. Two notes in Mrs Cook’s handwriting, expressing her wish to die, were found in the house but Cook, who has no previous convictions, was arrested on suspicion of murder.

During police interviews he admitted that he would now have to “live with what I’ve done” and added: “It’s not what they show you on the TV. It doesn’t take a couple of minutes. It takes longer.”

Christine Laing, QC, for the prosecution, said: “Her condition was deteriorating and he did not want her to suffer. It was his wife’s suggestion to put a bag over her head after seeing it done on television, in the event that the overdose alone would not work.”

Cook told police that he had asked Mrs Cook if she was sure she wanted him to do this and that she had nodded.Mrs Cook’s brother and sister supported Cook throughout the trial, calling his actions “brave and unselfish”.

Sentencing Cook, Judge Richard Brown, said: “Your wife, I’m wholly satisfied, had reached the limits of her personal endurance and as her full-time carer, you had done all you could do to care for her for many years.”

The judge said that the exceptional circumstances of the case meant that an immediate jail term was not necessary.

Euthanasia is illegal in every European state apart from the Netherlands and Belgium where, at the express and voluntary wish of the patient, a doctor may terminate their life.

In Switzerland, although euthanasia is officially illegal, assisted suicide is allowed and the country has become a destination for dozens of Britons seeking this option. A spokeswoman for Dignity in Dying, said: “When these cases do come to court, there is what the Law Commission called a ‘benign conspiracy’ and they are usually found guilty of manslaughter rather than murder.” This frees judges from having to impose a life sentence and gives them complete discretion as to the sentence.

She added: “The current law is failing terminally ill people and their loved ones and needs to be changed, if sad cases like this are to be avoided.”

In November last year, Stephen Jobling, 52, was handed a 12-month suspended prison sentence for aiding and abetting his wife’s suicide. Four months earlier, in May, Frank Lund, 58, was sentenced to life in prison after smothering his wife of 32 years with a pillow.

In May 2006, the House of Lords vetoed a Bill that would have enabled British doctors to practise a controlled form of euthanasia.

Sarah Wootton, the chief executive of Dignity in Dying, said: “At a time when he should have been treated with compassion and been allowed to grieve for his wife in peace, Robert Cook was arrested, charged with murder and forced to wait months to know whether or not he would be sent to prison.

“[The law] must change to allow terminally ill, mentally competent people to ask a doctor for help to die at a time and place of their choosing.”

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