The Nashville Metro Police Department said Charles Hargrave, 32, died from a fatal drug overdose in April.
An investigation showed Hargrave ordered the heroin from Natalie P. Neil, 31, on April 7, a short time before his girlfriend found him dead inside his home, police said.
According to a medical examiner, Hargrave died of a fentanyl overdose.
Fentanyl is an opioid that is often mixed with other drugs to enhance the effect. But, a small dose can be deadly.
The incident is still under investigation. Officials said Neil is being held on a $150,000 bond in Davidson County.