According to national newspaper La Nazione, the body was found in the town of Amelia in the central Italian province of Terni.
Previtali had reportedly been dating her 21-year-old boyfriend in the area for several months.
The night before her birthday the teen went out for a modest celebration with her friends, after which she went back to Francesco’s house for her special surprise.
According to La Nazione, Francesco allegedly gave her the heroin as a birthday present which she took in the early hours of the morning.
Reportedly, the emergency services received a call from Francesco at 8am on Saturday 10th October.
An ambulance arrived at the apartment but paramedics were unable to do anything but ascertain that she had died at the scene.
Francesco is reportedly now under investigation for an alleged delay in contacting the emergency services. It is thought that had the ambulance been called sooner, the victim could have been saved.
The father of Maria, who spent years working in an addiction recovery centre called Incontro, said: “Maria Chiara was not well, . . . . he influenced her, changed her. Since she started dating him she became a different person, unrecognizable. And now I find her dead.”
Previtali attended the fifth year of the Scientific high school “Renato Donatelli” in Terni and was a martial arts expert that also taught the sport.
Drugs and other substances were seized at the home of Francesco, known to the police as a drug addict, with a criminal record in the juvenile court.
Francesco allegedly told the police that they had gone to buy drugs the day before and it was to be her first time using heroin.
The investigation is now in the hands of prosecutor Camilla Coraggio, who has ordered an autopsy and will investigate the substances found at Francesco’s apartment.