The International Criminal Court (ICC) has terminated the case against Kenya's deputy president and ended his trial, saying there was insufficient evidence he was involved in violence that erupted after his country's 2007 presidential election.
The presiding judge wrote in the majority decision that the reason for the lack of evidence was possibly "witness interference and political meddling".
The announcement marks the second time the court has had to admit defeat in its attempts to prosecute the alleged ringleaders of the violence that left more than 1,000 people dead and forced 600,000 from their homes in Kenya.
Kenyan deputy president William Ruto had been charged alongside broadcaster Joshua Sang with murder, deportation and persecution for their alleged leading roles in the violence. The case against Mr Sang was also closed.
Supporters of the men cheered the decision, while human rights activists lamented that the victims of the violence had been denied justice.
Local TV in Kenya showed both men waving their arms in the air in celebration and being hugged by Mr Ruto's staff.
In Mr Ruto's home town of Eldoret, thousands of people took to the streets carrying placards, saying "Free at last" and "Ruto welcome home, you have suffered enough, you were innocent all the time".
A case against President Uhuru Kenyatta on similar charges collapsed in December 2014 amid prosecution claims of interference with witnesses and non-cooperation by authorities in Nairobi.
Three Kenyans have been charged with interfering with witnesses.
Abdrew Songa of the Kenya Human Rights Commission said "systematic witness tampering and intimidation experienced in the Kenya cases has denied thousands of victims of the post-election violence the justice they rightfully deserve".
Mr Kenyatta criticised the court for what he branded a decision to "blindly pursue (an) ill-conceived, defective agenda at the expense of accountability" for the violence and said the court had "given Kenyans false hope, and as a result, occasioned much disappointment".
He called in a tweet for Kenyans to attend a thanksgiving service at the Afraha Stadium in the Rift Valley town of Nakuru on April 16. Following the post-election violence, the stadium was used to house people forced from their homes.
Elizabeth Evenson, senior international justice counsel at Human Rights Watch, said Kenya's failure to prosecute perpetrators "leaves victims bereft of justice and the help they need". She said the Ruto trial "will likely be remembered for the reported efforts to corrupt witnesses".
In the decision, two members of the three-judge panel ordered the charges against Mr Ruto and Mr Sang to be dropped, although they said charges could be brought again if there is sufficient evidence.
According to a court statement, presiding judge Chile Eboe-Osuji said: "It cannot be discounted that the weaknesses in the prosecution case might be explained by the demonstrated incidence of tainting of the trial process by way of witness interference and political meddling."
Appeals judges ruled in February that statements made by five witnesses who later changed their stories or refused to testify against Mr Ruto and Mr Sang could not be used as evidence, a decision that likely sped up the case's collapse.
ICC prosecutors originally charged six Kenyans with crimes linked to the post-election violence. Charges have now been dropped against all six.