A HARWELL scientist tasked with measuring radiation in workers involved with the former USSR nuclear weapons programme stabbed himself to death, an inquest found.

Matthew Puncher, from Drayton, who discovered the amount of polonium found inside murdered Russian spy Alexander Litvinenko, was found dead in his home in May with wounds from two kitchen knives.

Oxford Coroner’s Court yesterday heard how the father-of-two worked for Public Health England in radiation protection dosimetry at Harwell and how his mood ‘completely changed’ after a visit to Russia before Christmas.

The 46-year-old had been given sole responsibility over a contract with the US Federal Government for a programme to measure the amounts of polonium inside Russian workers.

His wife Kathryn, along with work colleagues, revealed he had become obsessed with a mistake he had made in his research.

Home Office pathologist Dr Nicholas Hunt, who conducted the post mortem examination on weapons expert Dr David Kelly, said Mr Puncher was found dead at home with stab wounds to his arms, neck and upper abdomen.

Dr Hunt said he could not ‘entirely exclude’ third party involvement but was satisfied they were self-inflicted wounds and gave a cause of death as haemorrhaging due to stab and incised wounds.

The pathologist confirmed it was possible for someone to inflict the number of wounds Mr Puncher did before becoming unconscious.

His wife of 16 years, Kathryn Puncher, said: “He was always an upbeat and sensitive man. He was brilliant with the children as he was so intelligent and enjoyed helping them with their homework.

“After Christmas he changed completely. He just lost interest and I had to prompt him to do things like getting dressed and washing up, things he did without thinking before.

“He used to cook all the meals but he just stopped, he seemed to stop caring about anything.”

DC Rachel Clarke, who investigated the death, said: “It was very unusual, all the information told us he was very depressed and no-one in his family seemed particularly surprised he had taken his own life.

“But his injuries were so extensive, I didn’t know how he could have inflicted them on himself without becoming unconscious so we looked at the wider circumstances.”

But she added there was no evidence of a disturbance or a struggle, and no evidence of anyone else’s blood.

Head of department at Harwell, George Etherington, said Mr Puncher’s concerns his ‘coding error’ would land him prison for breaking a contract with the US Government was ‘irrational’, and a colleague described it as a ‘minor problem’.

Oxfordshire Coroner Nicholas Graham recorded a conclusion of suicide.