The world had tried to save Lennox, but ultimately, he could not be saved.
After two years of appeals by the 7-year-old dog's owners and sympathetic members of the international community, Belfast City Council confirmed that it had put the dog down on Wednesday.
Lennox was seized in April 2010 by dog wardens; pit bulls are illegal in Northern Ireland and Lennox had been deemed a danger to the public.
As Lennox's case went through the courts, the ruling to put him down continued to be upheld, and on Wednesday, the deadline for appeals expired.
Council members have received death threats from Lennox supporters, according to the BBC
. "We've had dog wardens who had to leave their homes," said Belfast City Council member Pat McCarthy. "We've had petrol poured through letter boxes, we've had people named on the web."
Lennox's family released a statement
prior to Lennox's death, saying that they had been "denied the opportunity to say goodbye."