WARNING: This article includes graphic detail of the execution
The execution of a man who allegedly confessed under duress to a crime he committed as a child, reflects Pakistani authorities' "callous indifference to human life", rights groups have said.
Shafqat Hussain was hanged on Tuesday for kidnapping and involuntary manslaughter after his death sentence kept being postponed amid concerns about the case.
It was the latest in at least 200 such killings since Pakistan restored the death penalty in December last year, Amnesty International said.
Campaigners said Mr Hussain, whose date of birth is disputed, was a teenager when he was sentenced in 2004 - not in his 20s as police claimed - for the killing of a seven-year-old.
There were worldwide calls for mercy and his family maintained he was innocent. "Why did they hang my innocent brother, only because we were poor?" his sister Sumaira Bibi asked.
His brother Abdul Majeed also claimed the execution was botched, telling AFP: "There is a cut mark on his neck and half of his neck is separated from his body."
David Griffiths, South Asia Research director at Amnesty International, called the hanging "another deeply sad day for Pakistan".
“A man whose age remains disputed and whose conviction was built around torture has now paid with his life - and for a crime for which the death penalty cannot be imposed under international law," he added.
“The government has shown a callous indifference to not just human life, but also to international law and standards.
"It has even ignored recommendations by one of its own bodies, the Sindh Human Rights Commission, to request the Supreme Court to consider the evidence relating to his juvenility and ‘confession’ extracted through torture."
He added Pakistan had executed at least 200 people in eight months and said this "must end immediately" with the government repealing the death penalty.
Mr Griffiths said: “It is too late to save Shafqat Hussain’s life, but there are still thousands of others on death row in Pakistan who are at risk."
Maya Foa, director of the death penalty team at Reprieve condemned Pakistan's "race to the gallows".
"[Mr Hussain] faced a catalogue of injustice, sentenced to death while still a child after being tortured by the police until he produced a so-called confession," she said.
"The government’s decision to push ahead with the execution despite calls to halt it from across Pakistan and around the world seems to have been more a show of political power than anything to do with justice.
"It is hard to see how anyone can now believe their claims that their enthusiastic resumption of hangings is anything to do with the safety and security of the country.”