It is possible to reveal that the tuberculosis in the alpaca, whose fate was decided by a legal battle lasting four years, did not exist.
Government vets took Geronimo to the end in August because of disputed claims that he was suffering from the disease.
Post-mortem tests on the animal showed no evidence of bovine tuberculosis.
Geronimo’s owner Helen Macdonald, 50, was adamant that he was not infected and launched a campaign to save him.
However, after losing the lengthy legal battle, officers were escorted to her Wickwar farm by police and took him away for execution.
Miss Macdonald (a registered veterinary nursing nurse) is looking into suing ministers regarding his killing.
The results of early testing in September did not indicate that the animal suffered from bovine tuberculosis.
Geronimo’s owner Helen Macdonald (pictured), 50, was adamant that he was not infected and launched a campaign to save him. After losing her long legal battle, she was finally defeated and officials, accompanied by police, dragged Geronimo from Wickwar in Gloucestershire to be executed.
No lesions were found on Geronimo’s lungs or respiratory tract – the most common place they are exhibited in an animal with the disease.
However, the Department for Environment, Food and Rural Affairs (Defra) said its vets had discovered a ‘number of TB-like lesions’ in the liver and lymph nodes.
Additional tests, which included developing bacteriological cultures of tissue samples from the animals to confirm the diagnosis, have been performed since. These tests were completed in the last week and showed no signs of the disease.
Miss Macdonald has previously called on Environment Secretary George Eustice to resign, accusing him of ‘murdering an innocent animal’.
Geronimo’s killing was the culmination of a David and Goliath legal fight between her and Defra that gripped the nation.
After two positive tests for bTB, the champion alpaca aged eight years old, which was originally born in New Zealand, was brought to Britain and sent for slaughter.
Miss Macdonald has always disputed the results – but the legal battle concluded with a High Court ruling in July that he should be destroyed.
In August, Defra officials and dozens of police officers forced their way on to Miss Macdonald’s farm to take Geronimo away.
She said Avon and Somerset Police had questions to answer for ‘facilitating murder’ and accused Defra of ‘bully boy tactics’ that are ‘frankly unforgivable’.
Miss Macdonald keeps a small herd alpacas, which she raises to produce luxury products at her farm. These include scarves and pashminas. The animals were first bred by her 19 years ago. Geronimo, a pedigree alpaca worth £15,000, had won competitions in New Zealand for his jet black wool.
Leading vets had demanded the Environment Secretary ‘commute Geronimo’s death sentence’ so he could be studied instead of slaughtered.
In September, early tests were not conclusive in determining whether the animal had bovine tuberculosis. (pictured in August being dragged away).
Thirteen experts urged Mr Eustice to call off the killing, allowing the alpaca to be ‘reserved for observation and treatment, whereby his immune responses may be non-invasively studied by a range of tests’.
This would help scientists understand bovine TB and improve accuracy of animal testing. Following Geronimo’s death, Boris Johnson’s father Stanley offered Miss Macdonald his condolences.
‘Nobody could have fought harder than you did,’ he said. ‘May he rest in peace.’
Defra had previously stated that it sympathized with Miss Macdonald, but had to address bovine TB. It said the animal’s removal was undertaken by trained and experienced Animal and Plant Health Agency (APHA) veterinarians in accordance with welfare guidelines.
Speaking at the time, chief veterinary officer Christine Middlemiss said: ‘No one wants to have to cull infected animals if it can be avoided, but we need to follow the scientific evidence and cull animals that have tested positive for bTB to minimise spread of this insidious disease and eradicate the biggest threat to animal health in this country.
‘Not only is this essential to protect the livelihoods of our farming industry and rural communities, but it is also necessary to avoid more TB cases in humans.’
Last night, Miss Macdonald as well Miss Defra were unwilling to speak out.