The 28-year-old faces up to fifteen years in prison after embarking on a shooting spree on February 4, following the sordid murder of a young Italian woman allegedly at the hands of Nigerian drug dealers.
Pamela Mastropietro's body was found dismembered and stuffed into suitcases days before Mr Traini's attack.
The two incidents, which occurred at the height of Italy's tense electoral campaign, shook the country and laid bare its deep tensions surrounding immigration.
Pro-migrant demonstrations across Italy condemning the attack were in contrast to an outpouring of support for Mr Traini who received messages of solidarity for his actions and, controversially, no politician paid a visit to his victims in hospital.
Security was tight outside the court in Macerata where Mr Traini faces charges of attempted murder and racial hatred.
The former security guard has admitted to the shooting but rejects allegations the attack was racially-motivated, insisting he wanted to target drug dealers.
"I wanted to hit the dealers, like those who sold the drugs to Pamela. It is not my fault that in Macerata all the dealers are black," he said during an interrogation released in Italian media.
His defence team has provided a psychiatric report which states that Mr Traini suffers from a personality disorder and that he was not completely aware of his actions at the time of the attack.
The hearing was the first time that Mr Traini's victims have come face to face with their attacker.
Speaking to the press, Aymere Innocent said: "We must pray for God to touch his heart."
The Nigerian pastor sustained wounds to his ear during the attack.