Guess Who

One evening, a male mortician died inside the funeral parlor that he owns. The parlor has been operating for ten years inside a big business center. Prior to the incident, seven friends of the mortician working within the same business center visited him in seven different days. The suspects are the following: a martial artist, a barber, a chef, a dentist, an engineer, a freelancer and a gangster. No physical evidence of homicide was found when the mortician died inside the said funeral parlor. However, the family members filed a case against all suspects who relied solely on statements submitted by witnesses in the last ten days before the mortician died. The initial report of the forensic experts stated that the mortician died of natural cause. Who do you think is the culprit?...