The Perugia court was asked to rule on whether Oseghale had also raped Mastropietro after supplying her with heroin.
The court found that sexual violence was also involved in the crime, which shocked Italy.
The mother of the murdered teenager, Alessandra Verni, attended the hearing wearing a T-shirt emblazoned with harrowing images of her daughter’s remains — including her decapitated head — on a pathologist’s table.
She said the extreme measure was in protest to Oseghale's appeal of part of his conviction.
Verni told Italian news outlet La Stampa that she wore the shirt as a “wake-up call,” saying that “after five years I am losing faith in justice.
“I wonder what is the point of re-prosecuting Oseghale, questioning sexual violence and opening up the possibility of a sentence reduction,” she told the daily newspaper.
Mastropietro's murder prompted a rightwing militant, Luca Traini, to shoot and wound six African migrants in a drive-by 'revenge' shooting in Macerata just days after her death.
He was sentenced to 12 years in jail for the attack in March 2021.
