Defendant killed the victim, 27, inside a residence in Osaka City's Higashinari Ward on February 16, 2017
Other residences tipped off police about a foul smell coming from the closet and 'a blood-stained bag on the balcony'
Man was found clutching a gun, police said
Father of victim said, 'This won't bring back my son'
Suspect bound the victim's hands inside a hotel in Taito Ward before the sexual assault took place
Suspect started the scam since victims would not lodge complaints with police due to the illegality of the drugs, police said
Husband is currently missing, police said
Suspect told police, 'I thought it was a nice product so I stole it'
Health of both persons had recently deteriorated, police said