Eight-year-old Margaash had got out of his £50,000 compound at Dudley Zoo, with staff saying there was "no other option" than to euthanise the big cat.
The zoo, in the West Midlands, said the decision was made to fatally shoot the animal "in the interest of public safety" after it escaped on October 23.
A spokesman said staff had tried to get the animal back in his enclosure but he was close to surrounding woodland, with dark approaching.
They added a tranquiliser would have taken too long to work.
Today, the zoo revealed a disciplinary investigation found the door of the enclosure had been left open due to "keeper error".
Dudley Zoo director, Derek Grove, said staff were "heartbroken" over the incident.
He said: "This was an incredibly sad incident and our staff are understandably heartbroken.
“Euthanasia is, and always will be, a last resort.
"Efforts to persuade Margaash to return to his enclosure failed and as the animal was close to surrounding woodland and dark was approaching, the vet did not believe a tranquilliser dart was a safe option due to the amount of time the drug takes to work.
“Safety of the public is always of paramount importance and our staff are highly experienced and rigorously trained."
There were no visitors at the zoo at the time.
The zoo said that Margaash was euthanised with a single shot.
Margaash had moved into the revamped enclosure in February this year.
The improvement project doubled the size of the enclosure to "give the animals more space and visitors better views of the big cats".
Since the news was revealed by the zoo, members of the public spoke out of their devastation.
COULD THEY HAVE BEEN SAVED? How Margaash the snow leopard is the latest animal to be shot dead in zoo emergency
THE death of the snow leopard Margaash has left animal lovers devastated.
Many have questioned why a tranquiliser was not used in the incident at the Dudley Zoo, despite the explanation from staff.
However, it's not the first time that zoos have come under fire for using firearms to deal with escaped animals.
One of the most notable cases was that of Harambe.
Harambe was a gorilla that was kept in Cincinnati Zoo, Ohio, who hit the headlines after he was shot by a worker at the tourist attraction.
After a three-year-old boy climbed into the enclosure, a zoo employee took the decision to shoot the primate for the tot's safety.
A bear was also shot dead after escaping from a German zoo earlier this year.
Residents had been warned to stay inside their homes after reports animals had escaped.
And in another incident this year, a lion was shot dead at a zoo in Belgium after escaping its cage.
The female lion escaped its enclosure at Planckendael Zoo, but did not get out of the zoo grounds.
One wrote on social media: "50k enclosure…Margaash escapes from it and is shot dead rather than tranquillised. Does not sound like 50k well spent.
"I await the results of your 'stringent review' into how Margaash escaped and hope those responsible are held accountable. The public deserve an explanation."
Another added: "it says in the report it was getting dark and he was in the woodland, they didn't think the tranq would work in time.
"It's heartbreaking, I've seen Margaash many times over the years, so stunning. In tears rn."
Visitors had recently "adopted" the much-loved snow leopard shortly after its death.
Margaash was born at Banham Zoo in Norfolk in May 2010 and came to Dudley Zoo in September 2011,
He lived with the three-year-old female Taïga.
Source: Read Full Article