A father spent £10,000 on private detectives after police failed to track down the thug who killed his daughter’s kitten with an air rifle. Neil Tregarthen devoted six weeks to gathering information for a 15-page report that named their prime suspect – but officers dismissed it as ‘rumour and speculation’ and abandoned the case. Yesterday the millionaire former business owner – who posed as an angler at one stage to spy on youths he believed were responsible – criticised the police investigation as ‘totally impotent’. Scroll down for video . Neil Tregarthen spent £10,000 on a private investigator after his daughter's cat, Farah, was shot by an air rifle . He and the private eyes identified several members of a local gang that posted Facebook pages of themselves injuring animals, and had criminal records for air rifle related offences. But police refused to bring a prosecution because of ‘lack of evidence’ for an attack that condemned Farah the kitten to a slow, agonising death. Mr Tregarthen’s daughter Aylish was horrified to find Farah lying in a pool of blood after limping home wounded and crippled with pain last September. The 24-year-old medical student and her father took the kitten to a vet but she suffered ‘a very long, painful, lingering death’ from a ruptured bowel and blood poisoning, finally passing away on the operating table, Mr Tregarthen said. When police told him there was not enough evidence to pursue the case he hired the detective firm and offered a £1,000 reward to catch the killer. They distributed flyers and set up a phone line for people to give information. It quickly became clear there had been a string of air rifle attacks near where Aylish lives in Exeter, Devon. ‘We narrowed it down to four youths, so we set about doing surveillance work,’ Mr Tregarthen said. ‘We would camp out on the river pretending to be fishing. We surveyed certain areas by pretending to be members of the public. Ideally we needed to witness an incident, but that never happened. We found a witness who claimed he had witnessed our main suspect shooting another cat.’ The kitten, pictured right with one of the family's other pets,  died despite extensive treatment at the vets . Mr Tregarthen is offering £1,000 to anyone with information which could lead to Farah's killer. The kitten was shot near her owner's home in Exeter . Exeter-based Focus Investigations, whose staff includes ex-police officers, said the person responsible had ‘an obvious sociopathic nature’. Mr Tregarthen, 56, added: ‘We compiled all the information we had, and presented it to the police. We did 85 per cent of the work – then Devon and Cornwall Police would not even go and knock on a couple of doors. Using an air rifle to shoot cats is illegal, and should be treated as such.’ Mr Tregarthen, who lives in a luxury house in Truro, Cornwall, said of the cost of his own investigation: ‘I would pay double that if I thought it would stop this sort of behaviour. 'I know I am in a fortunate position to be able to do so, but I think it is money well spent. It’s about society fighting back.’ Mr Tregarthen enlisted the help of private investigators Focus (offices pictured above) to help find Farah's killer . The animal is likely to have been playing in the garden when killed, Mr Tregarthen said. She returned to Miss Tregarthen's house wounded . His daughter said: ‘I feel like there is no justification for not investigating something that is illegal. We sympathise with the budget cuts – they have limited time and resources, which is why we chose to investigate it. But to still have the same response is very disappointing.’ Devon and Cornwall Police neighbourhood beat manager Steve Parsons said: ‘We investigated this crime fully. As for the investigation report, I have examined this and it is packed with rumour and speculation, not evidence. ‘However, on the back of this, officers did make further inquiries in the area which also turned out to be fruitless. I am confident we have done everything possible in investigating this case.’ Mr Tregarthen said police were 'impotent' in their investigations into who killed the cat, pictured above in a red collar . Mr Tregarthen lives in a plush £3million home in Truro, Cornwall (above). His daughter is studying medicine in Exeter .
Neil Tregarthen hired private investigators to look into the animal's death . Claimed local police in Exeter had been 'impotent' in their inquiries . The father of three put together a report which named a potential suspect . But officers dismissed it as 'packed with rumour and speculation'
Farah the kitten returned to owner's house wounded and bleeding to death .