He said the increasingly introduction of vigilantes in Ghanaian politics is tainting the country's image abroad.
Mahama, who is contesting to be NDC's flagbearer in 2020, showed the diplomats multiple videos of the barbaric attacks, gun violence, unrepentant admissions of responsibility by a Minister of State at the Presidency, Bryan Acheampong and videos of previous outings of the NPP government vigilante groups, Delta and Invincible Forces.
He also traced he history of the NPP’s introduction of the vigilante groups, their training and the dangerous decision to arm the hoodlums and also clothe them as supposed national security operatives.
On 31st January, masked security men purportedly to be National Security operatives shot and injured seven supporters of the NDC during the by-election.
John Mahama said "The violence took a different form, one it was state-sponsored because those who were involved in this were brought there by the state. They were armed to the teeth; they discharged weapons and injured several people. Unfortunately, that is not part of Ghana’s democratic culture. It was a day of shame for Ghana because Ghana has always been seen as the model of democracy in Africa".
The government has set up a Commission of enquiry into the incident which is being led by the former boss of CHRAJ, Justice Emile Short.
Mahama was joined by the the National Chairman, Samuel Ofosu Ampofo and General Secretary Johnson Asiedu Nketia of the National Democratic Congress (NDC), the Deputy Minority Leader James Avedzi, a former Minister for National Security Kofi Totobi Quakyi and senior members of the NDC.